chat: cleaning + some improvments: - code cleaning, removed some dead code - some improvments on the way size is calculated, removed unnecessary sizing methods which were linked to properties - image have now a max size, this avoid gigantic image in the whole screen - in SimpleXHTMLWidget, Label are now splitted when xhtml is set - use a DelayedBoxLayout for messages, as they are really slow to be resized - use of RecycleView has been investigated, but it is not currently usable as dynamic contents are not propertly handled (see https://github.com/kivy/kivy/issues/6580 and https://github.com/kivy/kivy/issues/6582). Furthermore, some tests with RecycleView on Android don't give the expected speed boost, so BoxLayout still seems like the way to go for the moment. To be re-investigated at a later point if necessary.

--- a/cagou/kv/simple_xhtml.kv	Fri Dec 06 13:23:03 2019 +0100
+++ b/cagou/kv/simple_xhtml.kv	Fri Dec 06 13:25:31 2019 +0100
@@ -14,10 +14,17 @@
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+#:import C cagou.core.constants.Const
+
+
+<SimpleXHTMLWidget>:
+    size_hint: 1, None
+    height: self.minimum_height
 
 <SimpleXHTMLWidgetEscapedText>:
-    size_hint: None, None
-    size: self.texture_size
+    size_hint: 1, None
+    text_size: self.width, None
+    height: self.texture_size[1]
 
 <SimpleXHTMLWidgetText>:
     size_hint: None, None