Deprecate closed.png and opened.png and enhance meta-contact display
Reasons to replace these two image files with collapse/expand arrows:
- It will fit better with system appearance.
- It will solve a trivial bug /ticket/7412#comment:4 bug in roster for RTL widget.
- It may save a few or some bytes (maybe).
- A GNOME software called Deskbar-Applet, which has a similar appearance to Gajim's roster, does use native collapse/expand arrows.
''Both of the main developers have dismissed this request. This is the final attempt, of mine, to persuade you to replace these images.