Terrain Images

[Stan Shebs <shebs@cygnus.com>]

I've just checked in the last of my series of changes that allow the
display to be constructed from images stashed in gifs.  This change
allows for the display of terrain using hex-shaped images rather than
patterns.  This will offer more flexibility, both in the shaping of
imagery to fit the hex shape, and in that you can specify a arbitrary
number of images for the display to choose from.  Right now the
standard terrain gif only has one for each type, except for desert -
and if you look closely at desert hexes in a game, you'll see two
slightly different images in use.

Eventually I'll fill in the rest of the big terrain gif, or someone
ambitious can try his own hand at it.  Once the dust settles a bit,
I'll document just how you can use this new machinery...

								Stan