[REF][FIX] mail, im_livechat: various improvements (JS)

This commit makes a lot of small improvements of the JS of mail and
related modules.

	A. Mail Manager
	---------------

		im_support:

		- [REF] Slightly more robust way to determine a support
		        message, so that it more reliably falls back on
		        default kind of message (i.e. support channel UUID
		        should be clearly set).

		mail:

		- [REF] Improved method names for readability purposes.
		        Some examples:

		        - `fetchFromServer` becomes `fetchMailStateFromServer`
		        - `_initialize{*}` becomes `_update{*}FromServer`
		        - `_isModerator` becomes `_isMyselfModerator`

		- [REF] Use 'template' pattern design to make Include on
				Mail Manager much more robust. In particular,
				the flow is always as follow:

					1. Initialize internal state.
					2. Listen on buses.
					3. Fetch mail data from server.

		- [REF] Improved workflow for thread window workflow
		        (Shorter & more readable).

	B. Mail Tests
	-------------

		- [REF] Thread Window Tests crashes with clean message when
		        there are some thread windows open before running the
		        tests.

	C. (Model) Message
	------------------

		- [REF] Improved method names for readability purposes
				(e.g. `isAuthor` becomes `isMyselfAuthor`).

	D. (Model) Thread
	-----------------

		- [REF] Improved `init` parameters on each kind of thread.
		- [REF] 'Thread With Cache' has been renamed to 'Searchable
		        Thread': it embraces all kinds of threads that can
		        be used with the search view.
		- [REF] 'DM' has been renamed to 'DM Chat' (for clarity).
		- [IMP] New Livechat model in the backend.
		- [REF] No more direct instances of the Channel class: public
		        and private channels are now 'Multi-User' channels,
		        while DM Chat and Livechat are 'Two-User' channels:

		        This change has been made so that instances of classes
		        always have direct classes as "leaf" in the Class
		        modeling. It eases making changes to a certain model
		        without being too constrained by another model.

		- [REF] As a consequence of above changed, the method `isChat`
		        has been renamed to `isTwoUserThread`.

		        This is to avoid confusion with the terminology
		        'chat', which is more like a shortcut for 'quick real-
		        time conversation'. In other words, the property of
		        'chat' depends of the way to interact on a thread, not
		        of the intrinsic type of the thread.

		        Still, some parts have kept the terminology 'chat',
		        such as in the systray messagin menu.

		- [IMP] Added `message_added` and `message_posted` hooks,
		        which may be useful to easily hook on those events.

	E. Thread Widget
	----------------

		- [REF] Now uses a `mail.model.AbstractThread` for the
		        rendering of a thread, instead of a list of
		        `{mail.model.AbstractMessage}`.
		- [FIX] Stick thread scroll height to bottom on new rendering,
		        if it was previously at the bottom of the thread.
		- [REF] Option ORDER has its meaning changed: it now refers
		        to the chronological order of messages in the thread,
		        in which DESC means 'from top to bottom', while ASC
		        means 'from bottom to top'.
		- [REF] Improved doc on templates, in particular with the
	            option `ORDER`.

	F. Thread Window
	----------------

		- [REF] Moved more logic to thread windows, which were
		        previously in Mail Window Manager.
		- [REF] Now hides the thread widget attribute. So instead of
		        `threadWindow.threadWidget.isAtBottom()`, it uses
		        `threadWindow.isAtBottom()`.
		- [FIX] New received messages when not having focus on Odoo
		        tab should always make the corresponding thread
		        windows "passive" (i.e. windows that keep threads
		        unread until click on them).
		- [FIX] Blank thread window (i.e. 'New message' TW) correctly
		        opens Discuss with 'Inbox' when clicking on 'Expand'
		        Button in the title
		- [FIX] Do not display the composer for channels with property
		        'mass-mailing' set in thread windows.

	G. (Website) Livechat
	---------------------

		- [REF] Some `trigger` have been turned into `trigger_up`.
		- [REF] Some logic has been moved to models (e.g.
		        `{im_livechat.model.WebsiteLivechat}`), from
		        `{im_livechat.im_livechat.LivechatButton}`.
		- [FIX] New messages should be received in real-time. The
		        longpolling was broken with a recent refactoring on
		        bus service (6448420c5dd160470e465dee7729d19d8d5e7bab).

1 files changed, 21 insertions, 17 deletions

diff --git a/addons/mail/static/src/js/thread_widget.js b/addons/mail/static/src/js/thread_widget.js
index ab0dea1bece..c2d642d5dbe 100644
--- a/addons/mail/static/src/js/thread_widget.js
+++ b/addons/mail/static/src/js/thread_widget.js
@@ -12,8 +12,8 @@ var QWeb = core.qweb;
 var _t = core._t;
 
 var ORDER = {
-    ASC: 1,
-    DESC: -1,
+    ASC: 1, // visually, chronological order of thread from bottom to top
+    DESC: -1, // visually, chronological order of thread from top to bottom
 };
 
 var READ_MORE = _t("read more");
@@ -55,7 +55,7 @@ var ThreadWidget = Widget.extend({
         // options when the thread is enabled (e.g. can send message,
         // interact on messages, etc.)
         this._enabledOptions = _.defaults(options || {}, {
-            displayOrder: ORDER.ASC,
+            displayOrder: ORDER.DESC,
             displayMarkAsRead: true,
             displayStars: true,
             displayDocumentLinks: true,
@@ -78,20 +78,16 @@ var ThreadWidget = Widget.extend({
             loadMoreOnScroll: this._enabledOptions.loadMoreOnScroll,
         };
         this._selectedMessageID = null;
+        this._currentThreadID = null;
     },
-
     /**
      * @override
      */
     destroy: function () {
         clearInterval(this._updateTimestampsInterval);
     },
-
     /**
-     * @param {mail.model.AbstractMessage[]} messages list of messages of the
-     *   thread, ordered by increasing IDs (a higher ID means a more recent
-     *   message).
-     * @param {}
+     * @param {mail.model.AbstractThread} thread the thread to render.
      * @param {Object} [options]
      * @param {integer} [options.displayOrder=ORDER.ASC] order of displaying
      *    messages in the thread:
@@ -99,11 +95,18 @@ var ThreadWidget = Widget.extend({
      *      - ORDER.DESC: last message is at the top of the thread
      * @param {boolean} [options.displayLoadMore]
      * @param {boolean} [options.isCreateMode]
+     * @param {boolean} [options.scrollToBottom=false]
      * @param {boolean} [options.squashCloseMessages]
      */
     render: function (thread, options) {
         var self = this;
 
+        var shouldScrollToBottomAfterRendering = false;
+        if (this._currentThreadID === thread.getID() && this.isAtBottom()) {
+            shouldScrollToBottomAfterRendering = true;
+        }
+        this._currentThreadID = thread.getID();
+
         // copy so that reverse do not alter order in the thread object
         var messages = _.clone(thread.getMessages());
 
@@ -115,9 +118,6 @@ var ThreadWidget = Widget.extend({
             return message.getAttachments();
         })));
 
-        if (modeOptions.displayOrder === ORDER.DESC) {
-            messages.reverse();
-        }
         options = _.extend({}, modeOptions, options, {
             selectedMessageID: this._selectedMessageID,
         });
@@ -160,6 +160,11 @@ var ThreadWidget = Widget.extend({
             }
             prevMessage = message;
         });
+
+        if (modeOptions.displayOrder === ORDER.DESC) {
+            messages.reverse();
+        }
+
         this.$el.html(QWeb.render('mail.widget.Thread', {
             thread: thread,
             displayAuthorMessages: displayAuthorMessages,
@@ -175,6 +180,10 @@ var ThreadWidget = Widget.extend({
             self._insertReadMore($message);
         });
 
+        if (shouldScrollToBottomAfterRendering) {
+            this.scrollToBottom();
+        }
+
         if (!this._updateTimestampsInterval) {
             this.updateTimestampsInterval = setInterval(function () {
                 self._updateTimestamps();
@@ -368,11 +377,6 @@ var ThreadWidget = Widget.extend({
             });
         });
     },
-
-    //--------------------------------------------------------------------------
-    // Private
-    //--------------------------------------------------------------------------
-
     /**
      * @private
      * @param {Object} options