New agent Browser (JEP 30 complient)
Upgrade of french translation

exit chatroom when closing the window

do not create a new connexion in the core if it already exists

save events when no visual plugin (like gtkgui) is registered and restore them when such a plugin resiters

gtkgui plugin ask roster when it starts (in case an account is already conected)\nthread in started in plugin.py

new QUIT signal : we can or not close the core

runCore can now recieve the -c option to be lunch as a client. In such a case, it connects to a gajim server (a sock plugin) and not to a jabber server

new ImageCellRenderer to show pixbuf and pixbufAnimation in treeview (take less CPU time than the old method)

new preference option : icon in systray (changement is tacken into account at next start)

somedays read_queue would have to be a common share code and thus no specific
plugin code could be call from there.

(untested: not able to compile C module trayicon)