Reset all of menv in tag_read_level_monsters(). Fixes bug where

sometimes floating monstes would be detected by debug_mons_scan() when going from one level to another, but the problem would be fixed if you saved and restored the game.

In tag_read_level_monsters() if DEBUG or DEBUG_MONS_SCAN is defined give an error message if restoring a monster onto a square which already has a monster.

git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@7634 c06c8d41-db1a-0410-9941-cceddc491573

Created by  zelgadis  on November 26, 2008
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