Hopefully repeat my previous changes for trunk:

documentation and index/offset fix.

git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@2135 c06c8d41-db1a-0410-9941-cceddc491573

Created by  j-p-e-g  on September 18, 2007
FYD4A5TIETIV2ZLFYWGHXANU6WQFKMVREHM7OZY2TAXSBMMCDLJAC
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