New icons and symlinks

Hey,

I've made some icons for aegisub, dolphin-emu, guake, hexchat, mumble, nvidia and xbmc. I only added the 256 sizes for these icons, have you got an automated way of scaling SVG? Doing it by hand using Inkscape is quite tedious. Also added symlinks from VBox to virtualbox.

What do you think?

Cheers,
--
Maxime