010

Aug 14th,
- added an inRange() function and a constant ZOMBIE_AI_RANGE, as well as
some new logic in handleZombies to try and curb zombie trains.
...zombies should only chase after the player if they are within range
of the player.
- added addtional constants for the "extreme" difficulty with
ghost-zombies
- had to make a change to how tilemap.move handles maximum bounds - it
was bugged after the change to scrollMap
- 1 last minor tweak to tilemap.randomPos...was some bad logic. Also
commented out "inRange" in handleZombies for testing. will uncomment on
next iteration