Add miscellaneous minor cleanups to prepare for the introduction of

Yred's injury mirroring: move the routine to make a visible monster flash a particular color into its own function, add an integer-based square root function based on Newton's method to stuff.cc, and adjust prayer lengths for Zin (1 turn), Yred (20 turns), Ely (same as Yred), and all gods who ignore prayers (same as Zin).

git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/trunk@6982 c06c8d41-db1a-0410-9941-cceddc491573

Created by  dolorous  on September 25, 2008
RWH6IAVXQD3Q7ITNN5WOOUHBDBYURLXFEURA7QFHS4ZED2CG7MOQC
Change contents