[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, 31 insertions, 0 deletions

diff --git a/addons/mail/static/src/scss/thread.scss b/addons/mail/static/src/scss/thread.scss
index b724c7fb241..12bd5a3af70 100644
--- a/addons/mail/static/src/scss/thread.scss
+++ b/addons/mail/static/src/scss/thread.scss
@@ -3,6 +3,37 @@
         text-align: center;
     }
 
+    .o_thread_bottom_free_space {
+        height: 15px;
+    }
+
+    .o_thread_tooltip_container {
+        display: inline;
+        position: relative;
+
+        .o_thread_tooltip_content {
+            top: 10px;
+            background: $gray-lighter;
+            padding: 4px;
+            border: solid $gray-lighter 1px;
+            border-radius: 5px;
+            color: gray;
+            width: 300px;
+            display: none;
+            opacity: 0;
+            position: absolute;
+            transition: opacity 0.5s;
+            i.fa-exclamation {
+                color: red;
+            }
+        }
+
+        .o_thread_tooltip:hover + .o_thread_tooltip_content {
+            display: inline;
+            opacity: 1;
+        }
+    }
+
     .o_thread_date_separator {
         margin-top: 15px;
         margin-bottom: 30px;