Adding spell images, rltiles build script, and a tileidx_spell function. There are quite a few spells that don't have images (marked as TODO in tileidx_spell) and about three images that are named "unknown" because I can't figure out what they map to.

git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@10651 c06c8d41-db1a-0410-9941-cceddc491573

Created by  ennewalker  on September 10, 2009
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