git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@2824 c06c8d41-db1a-0410-9941-cceddc491573
HHVSLL26MH52H7L3JJO7CJCE43VICS3XTO4AQDVJKDZ4AXGKFJVQC
4KZCX2DSUCAWFYONVHEM7EXGF3KNNKZEIA2N3Z6ICLBQLQJHOG5AC
K2CS6TCX2NDVL2ASEHGP4J4K4IJ6FP3ANNKTSIWVG43HPYSBX6ZQC
int min_x = GXM, max_x = 0, min_y = GYM, max_y = 0;
int min_x = GXM-1, max_x = 0, min_y = GYM-1, max_y = 0;