common caching mechanism for xfdesktop and xfce4-appfinder

[Eduard Roccatello]

Hello devs! (and not :-)

Some time ago we was talking about a common cache for .desktop
files usable by every apps in xfce desktop suite.
I'm thinking about rewriting the indexing mechanism of
xfce4-appfinder widget (yeah i know... i haven't committed
anything :o) ...but some things are broken and i need to fix
before committing and obviously time lacks).

So... ehm... what about the cache? :-)
We need something abstract enough for everyday use.

Cheers,
Eduard