added health fields and accessors in player and monster
added more combat fields to player and monster, added debug drawing for combat
cleaned up combat stuff
first pass monster killing
first path player following in monster pathing, exposed bug in monster pathing not yet fixed
tweaked monster pathing a little, removed some prints
added ref to gesture listener doc for future input processing
no functional change
fixed bug where monster would not walk all the way to destination:
organizational changes, no func. change
more organization, no func change