Allow non-rectangular minivaults and branch entry vaults (use space padding).

They're still rectangular for collision detection with other vaults; that'll need more effort to fix.

Space padding can also be used for regular vaults, but it'll be ignored at the moment (but soon…! :-)).

git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@1778 c06c8d41-db1a-0410-9941-cceddc491573

Created by  dshaligram  on July 6, 2007
CREW3VTGN2BV622ZXHCPHUEZWBAGEQMNUELDLTHLEKG4VBXGMRPQC
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