Move tutorial ending check from gain_exp() to level_change(), so that if

the player gains XL 7 via a potion of experience the tutorial will end.

git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@9815 c06c8d41-db1a-0410-9941-cceddc491573

Created by  zelgadis  on May 24, 2009
5CCSNK7JAF3CVSABERMIUNZAJI6JNAY7WIOA64BRDZWJXKTLQ3KQC
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