"Add to panel" dialog and dapper plan

[Manu Cornet]

Hi !

I have been working tonight on the "Add to panel" part of the Dapper
plan :

	https://wiki.ubuntu.com/DapperDesktopPlan

Since I originally designed the new dialog, the least I could do was
tidy it a little bit, as asked :)

So here's the patch (for seb128) :
	http://www.manucornet.net/GNOME/code/panel_addto_dapper_plan.diff

(apply it after patches 11 and 12), and here's a screenshot (not a
mockup) :

	http://www.manucornet.net/GNOME/Capture.png

(since the "description" string couldn't be shown as with other applets,
I just used tooltips on these two buttons. I also added accelerators for
them.)

Cheers,
Manu