Add new condition SpellKnown() to test for a spell in the spellbook.

git-svn-id: svn+ssh://svn.curseforge.net/wow/ovale/mainline/trunk@878 d5049fe3-3747-40f7-a4b5-f36d6801af5f
Fix for ticket 215 - Memory leak?

Invert design by replacing a stateful iterator with a callback.  This
avoids the (temporary) memory used by Lua to create and store closures.

git-svn-id: svn+ssh://svn.curseforge.net/wow/ovale/mainline/trunk@879 d5049fe3-3747-40f7-a4b5-f36d6801af5f