Fix monsters not entering map edge.

git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@10180 c06c8d41-db1a-0410-9941-cceddc491573

Created by  j-p-e-g  on July 12, 2009
CKZAVAV4E2XURUGQOEBWEIHHSWEOFHGEW7RF5DG6GWTKR4NSLRHQC
Change contents