Fix trunk compile, and a bit of code clean-up.

Oh, and filter MSGCH_PROMPT from message history.

git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@3488 c06c8d41-db1a-0410-9941-cceddc491573

Created by  j-p-e-g  on February 29, 2008
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