tiles.rc: rename tiles.dat to tiles.rc, bring TileSpec into main program

git-svn-id: https://micropolis.googlecode.com/svn/trunk/micropolis-java@730 d9718cc8-9f43-0410-858b-315f434eb58c
tiles.rc: add comments to delineate different categories

git-svn-id: https://micropolis.googlecode.com/svn/trunk/micropolis-java@731 d9718cc8-9f43-0410-858b-315f434eb58c
tile animation: animation is now controlled by tiles.rc

git-svn-id: https://micropolis.googlecode.com/svn/trunk/micropolis-java@732 d9718cc8-9f43-0410-858b-315f434eb58c
docs: fix typo in HACKING document
MakeTiles: impl generation of different-sized tiles
MakeTiles: allow tiles recipe to be more size-agnostic
tiles.rc: make source size specifications optional, since it's always 16x16