Improve encapsulation of OvaleFuture and improve memory usage.

Improve encapsulation of OvaleFuture and improve memory usage.

Make some unnecessarily public tables private and provide descriptive
accessor methods to access those tables.

Be slightly more memory-efficient in OvaleFuture by using a table pool
managed by OvalePool to avoid creating then throwing away small tables
each time the player casts a spell.

Also rename some variables in OvaleFuture to make it more clear what the
contents of those variables contain.

git-svn-id: svn://svn.curseforge.net/wow/ovale/mainline/trunk@815 d5049fe3-3747-40f7-a4b5-f36d6801af5f