Fix listing of hydra head listing to show the correct amount when heads

get sliced off and regrow, and also apply the naming change to hydra zombies.

git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@5030 c06c8d41-db1a-0410-9941-cceddc491573

Created by  j-p-e-g  on May 14, 2008
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