Clean up acquirement subtype determination code. (Another goto bites the dust.)

Be a bit more generous regarding books for Evoc and Invoc types.

git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@8890 c06c8d41-db1a-0410-9941-cceddc491573

Created by  haranp  on February 4, 2009
OE3TD4J5FSIFAM37J2UPEV7QQNXLSZM6GDUMPI66LC5LW2OM2J4AC
Dependencies
In channels
main
Change contents