restructure: move bin/ and tests/ to src/

Also add symlinks from the old `bin/` and `tests/` locations to avoid
breaking scripts and other tools.

Motivations:

  * Scripts and tests no longer have to do dubious things like:

        require('ep_etherpad-lite/node_modules/foo')

    to access packages installed as dependencies in
    `src/package.json`.

  * Plugins can access the backend test helper library in a non-hacky
    way:

        require('ep_etherpad-lite/tests/backend/common')

  * We can delete the top-level `package.json` without breaking our
    ability to lint the files in `bin/` and `tests/`.

    Deleting the top-level `package.json` has downsides: It will cause
    `npm` to print warnings whenever plugins are installed, npm will
    no longer be able to enforce a plugin's peer dependency on
    ep_etherpad-lite, and npm will keep deleting the
    `node_modules/ep_etherpad-lite` symlink that points to `../src`.

    But there are significant upsides to deleting the top-level
    `package.json`: It will drastically speed up plugin installation
    because `npm` doesn't have to recursively walk the dependencies in
    `src/package.json`. Also, deleting the top-level `package.json`
    avoids npm's horrible dependency hoisting behavior (where it moves
    stuff from `src/node_modules/` to the top-level `node_modules/`
    directory). Dependency hoisting causes numerous mysterious
    problems such as silent failures in `npm outdated` and `npm
    update`. Dependency hoisting also breaks plugins that do:

        require('ep_etherpad-lite/node_modules/foo')

src/tests/frontend/helper/methods.js

@@ -0,0 +1,238 @@
+'use strict';
+
+/**
+ * Spys on socket.io messages and saves them into several arrays
+ * that are visible in tests
+ */
+helper.spyOnSocketIO = function () {
+  helper.contentWindow().pad.socket.on('message', (msg) => {
+    if (msg.type === 'COLLABROOM') {
+      if (msg.data.type === 'ACCEPT_COMMIT') {
+        helper.commits.push(msg);
+      } else if (msg.data.type === 'USER_NEWINFO') {
+        helper.userInfos.push(msg);
+      } else if (msg.data.type === 'CHAT_MESSAGE') {
+        helper.chatMessages.push(msg);
+      }
+    }
+  });
+};
+
+/**
+ * Makes an edit via `sendkeys` to the position of the caret and ensures ACCEPT_COMMIT
+ * is returned by the server
+ * It does not check if the ACCEPT_COMMIT is the edit sent, though
+ * If `line` is not given, the edit goes to line no. 1
+ *
+ * @param {string} message The edit to make - can be anything supported by `sendkeys`
+ * @param {number} [line] the optional line to make the edit on starting from 1
+ * @returns {Promise}
+ * @todo needs to support writing to a specified caret position
+ *
+ */
+helper.edit = async function (message, line) {
+  const editsNum = helper.commits.length;
+  line = line ? line - 1 : 0;
+  helper.linesDiv()[line].sendkeys(message);
+  return helper.waitForPromise(() => editsNum + 1 === helper.commits.length);
+};
+
+/**
+ * The pad text as an array of divs
+ *
+ * @example
+ * helper.linesDiv()[2].sendkeys('abc') // sends abc to the third line
+ *
+ * @returns {Array.<HTMLElement>} array of divs
+ */
+helper.linesDiv = function () {
+  return helper.padInner$('.ace-line').map(function () {
+    return $(this);
+  }).get();
+};
+
+/**
+ * The pad text as an array of lines
+ * For lines in timeslider use `helper.timesliderTextLines()`
+ *
+ * @returns {Array.<string>} lines of text
+ */
+helper.textLines = function () {
+  return helper.linesDiv().map((div) => div.text());
+};
+
+/**
+ * The default pad text transmitted via `clientVars`
+ *
+ * @returns {string}
+ */
+helper.defaultText = function () {
+  return helper.padChrome$.window.clientVars.collab_client_vars.initialAttributedText.text;
+};
+
+/**
+ * Sends a chat `message` via `sendKeys`
+ * You *must* include `{enter}` at the end of the string or it will
+ * just fill the input field but not send the message.
+ *
+ * @todo Cannot send multiple messages at once
+ *
+ * @example
+ *
+ * `helper.sendChatMessage('hi{enter}')`
+ *
+ * @param {string} message the chat message to be sent
+ * @returns {Promise}
+ */
+helper.sendChatMessage = function (message) {
+  const noOfChatMessages = helper.chatMessages.length;
+  helper.padChrome$('#chatinput').sendkeys(message);
+  return helper.waitForPromise(() => noOfChatMessages + 1 === helper.chatMessages.length);
+};
+
+/**
+ * Opens the settings menu if its hidden via button
+ *
+ * @returns {Promise}
+ */
+helper.showSettings = function () {
+  if (!helper.isSettingsShown()) {
+    helper.settingsButton().click();
+    return helper.waitForPromise(() => helper.isSettingsShown(), 2000);
+  }
+};
+
+/**
+ * Hide the settings menu if its open via button
+ *
+ * @returns {Promise}
+ * @todo untested
+ */
+helper.hideSettings = function () {
+  if (helper.isSettingsShown()) {
+    helper.settingsButton().click();
+    return helper.waitForPromise(() => !helper.isSettingsShown(), 2000);
+  }
+};
+
+/**
+ * Makes the chat window sticky via settings menu if the settings menu is
+ * open and sticky button is not checked
+ *
+ * @returns {Promise}
+ */
+helper.enableStickyChatviaSettings = function () {
+  const stickyChat = helper.padChrome$('#options-stickychat');
+  if (helper.isSettingsShown() && !stickyChat.is(':checked')) {
+    stickyChat.click();
+    return helper.waitForPromise(() => helper.isChatboxSticky(), 2000);
+  }
+};
+
+/**
+ * Unsticks the chat window via settings menu if the settings menu is open
+ * and sticky button is checked
+ *
+ * @returns {Promise}
+ */
+helper.disableStickyChatviaSettings = function () {
+  const stickyChat = helper.padChrome$('#options-stickychat');
+  if (helper.isSettingsShown() && stickyChat.is(':checked')) {
+    stickyChat.click();
+    return helper.waitForPromise(() => !helper.isChatboxSticky(), 2000);
+  }
+};
+
+/**
+ * Makes the chat window sticky via an icon on the top right of the chat
+ * window
+ *
+ * @returns {Promise}
+ */
+helper.enableStickyChatviaIcon = function () {
+  const stickyChat = helper.padChrome$('#titlesticky');
+  if (helper.isChatboxShown() && !helper.isChatboxSticky()) {
+    stickyChat.click();
+    return helper.waitForPromise(() => helper.isChatboxSticky(), 2000);
+  }
+};
+
+/**
+ * Disables the stickyness of the chat window via an icon on the
+ * upper right
+ *
+ * @returns {Promise}
+ */
+helper.disableStickyChatviaIcon = function () {
+  if (helper.isChatboxShown() && helper.isChatboxSticky()) {
+    helper.titlecross().click();
+    return helper.waitForPromise(() => !helper.isChatboxSticky(), 2000);
+  }
+};
+
+/**
+ * Sets the src-attribute of the main iframe to the timeslider
+ * In case a revision is given, sets the timeslider to this specific revision.
+ * Defaults to going to the last revision.
+ * It waits until the timer is filled with date and time, because it's one of the
+ * last things that happen during timeslider load
+ *
+ * @param {number} [revision] the optional revision
+ * @returns {Promise}
+ * @todo for some reason this does only work the first time, you cannot
+ * goto rev 0 and then via the same method to rev 5. Use buttons instead
+ */
+helper.gotoTimeslider = function (revision) {
+  revision = Number.isInteger(revision) ? `#${revision}` : '';
+  const iframe = $('#iframe-container iframe');
+  iframe.attr('src', `${iframe.attr('src')}/timeslider${revision}`);
+
+  return helper.waitForPromise(() => helper.timesliderTimerTime() &&
+      !Number.isNaN(new Date(helper.timesliderTimerTime()).getTime()), 10000);
+};
+
+/**
+ * Clicks in the timeslider at a specific offset
+ * It's used to navigate the timeslider
+ *
+ * @todo no mousemove test
+ * @param {number} X coordinate
+ */
+helper.sliderClick = function (X) {
+  const sliderBar = helper.sliderBar();
+  const edown = new jQuery.Event('mousedown');
+  const eup = new jQuery.Event('mouseup');
+  edown.clientX = eup.clientX = X;
+  edown.clientY = eup.clientY = sliderBar.offset().top;
+
+  sliderBar.trigger(edown);
+  sliderBar.trigger(eup);
+};
+
+/**
+ * The timeslider text as an array of lines
+ *
+ * @returns {Array.<string>} lines of text
+ */
+helper.timesliderTextLines = function () {
+  return helper.contentWindow().$('.ace-line').map(function () {
+    return $(this).text();
+  }).get();
+};
+
+helper.padIsEmpty = () => (
+  !helper.padInner$.document.getSelection().isCollapsed ||
+  (helper.padInner$('div').length === 1 && helper.padInner$('div').first().html() === '<br>'));
+
+helper.clearPad = async () => {
+  if (helper.padIsEmpty()) return;
+  const commitsBefore = helper.commits.length;
+  const lines = helper.linesDiv();
+  helper.selectLines(lines[0], lines[lines.length - 1]);
+  await helper.waitForPromise(() => !helper.padInner$.document.getSelection().isCollapsed);
+  const e = new helper.padInner$.Event(helper.evtType);
+  e.keyCode = 8; // delete key
+  helper.padInner$('#innerdocbody').trigger(e);
+  await helper.waitForPromise(helper.padIsEmpty);
+  await helper.waitForPromise(() => helper.commits.length > commitsBefore);
+};