Buggy line of sight with infinite range done.

Line of sight seems to be working (monsters can spot you when there is
nothing blocking the way).  But it seems to bug out when you change
floors (I got a few null pointer exceptions after using stairs).
Fixed null pointer exception on new level

Fixed the null pointer exception that happened when you changed levels
or when you first start the game.
Added in sight range and fixed bugs

Added in custom sight ranges for monsters and fixed some bugs in the old
line of sight code.
Merge branch 'master' of https://github.com/apepers/599-roguelike

Conflicts:
	Roguelike/src/entities/Monster.java