Optimizations and cleaning for Lubuntu

Work items :
[rafaellaguna] Make a new theme, with clearloooks and adwaita engines : DONE
[gilir] Migrate osmo to GTK3 (to get rid of webkit + gtk2) : POSTPONED
Glade: Migrate galculator : POSTPONED
Glade: Migrate obconf : POSTPONED
Glade: Migrate xfburn / libxfcegui4-4 (maybe already done by migration to libxfceui : POSTPONED
Glade: Migrate xscreensaver (?) : POSTPONED
Introspection: Evaluate removing python-gtk2 : POSTPONED
Introspection: Evaluate removing python-vte : POSTPONED
Introspection: Evaluate removing python-notify : POSTPONED

Notes during the session :

GTK3 :
- Big parts of the desktop will probably not be migrated for 12.04 : file-manager, panel, browser
=> Keep GTK2, and try to work on some applications for future switch

Theme:
- The new theme should be more lightweight than the one we had on 11.10

Other items:
- Try to do our best to improve the situation

=================================================================
Kill gconf - see https://live.gnome.org/GnomeGoals/GSettingsMigration
abiword : TODO
chromium : TODO
gdebi : TODO
gecko-mediaplayer : TODO
gksu : TODO
gnome-mplayer : TODO
gnome-user-share : TODO
gucharmap : TODO
network-manager-gnome : TODO
pidgin : TODO
update-notifier : TODO

Kill glade - see http://developer.gnome.org/gtk/2.24/gtk-migrating-GtkBuilder.html
Migrate galculator : TODO
Migrate obconf : TODO
Migrate xfburn / libxfcegui4-4 : TODO
Migrate xscreensaver (?) : TODO

GTK3 migration
Upload GTK3 packages for LXDE ready : TODO
libfm & pcmanfm : TODO
lxpanel : TO DISCUSS
Chromium (http://code.google.com/p/chromium/issues/detail?id=79722): BLOCKED
Abiword : TO DISCUSS (Xubuntu)
Audacious (available on 2.5, discuss with maintainer): TODO
galculator : TODO
obconf : TODO
synaptic (work in progress by upstream) : IN PROGRESS
Gnumeric : TO DISUCSS (Xubuntu)
system-config-printer : TODO
leafpad (fix available on http://gnomefiles.org/content/show.php/L3afpad?content=144892, need discussion with Xubuntu) : TO DISCUSS
lxkeymap (blocked by python-xklavier and its rdepends) : BLOCKED
gnome-mplayer (available by adding a flag, see bug 817933) : TODO
pidgin (work in progress upstream http://developer.pidgin.im/wiki/GTK3) : IN PROGRESS
osmo : TODO
hardinfo : TODO
sylpheed : TODO
transmission (available in version 2.40) : TODO
gnome-time-admin (upstream doesn't plan to migrate it, see also problem with polkit-gtk) : BLOCKED
Xfburn (not planned in short-term by upstream) : BLOCKED
xpad (see upstream https://launchpad.net/xpad): TODO
guvcview (work in progress upstream, https://launchpad.net/guvcview, rev 753): IN PROGRESS
mtpaint : TODO

Various optimization
Replace update-notifier with something which use less memory.