[Added] getLowestHeight method to terrain manager.
[Added] getHighestHeightDifference method to terrain manager.
[Added] test for terrain manager.
[Added] getSpawnArea method to director manager.
[Changed] Lair spawns to only spawn on 20 x 20 areas where the height
difference is less than 10. (random spawns and mission spawns)

Change-Id: I7b85b3720b730eb1fc6b2d9319decede2b16da62
Merge "[Added] getLowestHeight method to terrain manager. [Added] getHighestHeightDifference method to terrain manager. [Added] test for terrain manager. [Added] getSpawnArea method to director manager. [Changed] Lair spawns to only spawn on 20 x 20 areas where the height difference is less than 10. (random spawns and mission spawns)" into unstable