core (common): new Symbol widget: it uses font icon to display a symbol by name (should move to direct svg rendering once it's stable in Kivy). bg_color property allows to change background color. margin property allows to display a margin around the symbol

--- a/cagou/core/image.py	Fri Apr 06 16:13:08 2018 +0200
+++ b/cagou/core/image.py	Fri Apr 06 16:13:08 2018 +0200
@@ -81,4 +81,3 @@
             self.source = self.source[7:]
         else:
             super(AsyncImage, self)._load_source(*args)
-