[crossfire] Arch repository: layered art files?

[Kevin R. Bulgrien]

While working on a couple new graphics (based on existing ones), I made heavy
use of layers.  I could grab elements from other arch tiles, put them on a
layer (reuse), and then use layers to add unique features.

In one case, I drew a tile from scratch, but used layers to hold particular
components of the tile so that it was easy to rework different aspects of
the tile... especially those involving curves, filters, randomness, etc.

Putting only the .png in SVN feels like putting a pre-compiled object into
the repository... useful... but... not exactly conducive to facilitating any
type of rework.

Does anyone else think that putting the source files into SVN is a good idea,
or just extra clutter?  I realize, for example, my source files are likely
GIMP-specific, and I suppose each artist's favorite editor uses a different
format.  That might be the biggest obstacle.  The next, perhaps, that artists
come few and far between, so the likelihood of actual use may be very low,

Beyond that, if it seems a good idea to various people, what file format 
preferences are out there?

Kevin