Expand mutate() to account for mutations as god gifts, and make Xom use

them, so that he respects the full mutation resistance mutation, as well as the limitations on how much players can be covered in scales, etc.

git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@4666 c06c8d41-db1a-0410-9941-cceddc491573

Created by  dolorous  on April 26, 2008
CQMX53TEZCRYKPNWUSNMMRRYBTRDF4Z4LXZWD7CSCZH6GDVDEK7QC
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