better native tray support for *nix

[totaam]

We already have native X11 code for dealing with the system tray server side (see [/browser/xpra/trunk/src/xpra/x11/gtk_x11/tray.py xpra/x11/gtk_x11/tray.py]), but at the moment only win32 has native tray support (see [/browser/xpra/trunk/src/xpra/platform/win32/win32_tray.py xpra/platform/win32/win32_tray.py]).

The gtk.StatusIcon we use is too limited:

• does not let us catch hover events,
• does not let us catch individual clicks (only "activate" and "popup" events)

It shouldn't be too hard to do better than that. Either with native X11 code or with another/better tookit (see #388 for Qt)

[totaam]

2013-08-08 06:52:13: totaam uploaded file qttray.py (0.5 KiB)

simple qt tray example

[totaam]

2013-08-08 06:53:07: totaam uploaded file wxtray.py (1.1 KiB)

simple wx tray example

[totaam]

2013-08-08 06:56:24: totaam uploaded file pythonicon.py (3.7 KiB)

simple gtk + xlib tray example (GPL taken from awn-extras-applets)

[totaam]

win32 has this already, it would be a shame if *nix did not!

Let's try not to undo #479 when we do it.

[totaam]

Won't help now that gnome doesn't support ANY system trays.. and then there's wayland.