Implement MAXHP, MAXMP

[AdamBissonnette]

MAXHP and MAXMP should be implemented in such a way as to promote efficiency when waiting to heal or deciding when to cast vigor. If the character is nearly full health then casting a heal or using a restorative item shouldn't be done.

[lbaribeau]

I think max hp and max mp are just variables that hold those two values. There are other variables, like health_to_go, involved in the logic that decides to leave the chapel before completely maxed. I've made a lot of changes in this area recently, like less casting vigor. It now estimates the hp regen rate and mp regen rate and tries to level them off so they'll complete at the same time. I think more can be done. Maybe we can close this though.