since they old ones we had had scaling artifacts on the edges, and they have been
split up into one file per texture. We now also use custom mipmaps down to 16x16
size for improved scaling and interpolation. Texture page (atlas) assembly is now
done with OpenGL rather than by shuffling pixels directly in memory.
git-svn-id: svn+ssh://svn.gna.org/svn/warzone/trunk@2300 4a71c877-e1ca-e34f-864e-861f7616d084