Added GridZones that detect when units pass through them
Replaced some reference variables to use inter ids instead
Rooms are now separate constructs stored within the GridManager
Added MESSAGE_TYPE_GRID_UNIT_COLLISION that fires when one unit attempts to move into a cell occupied by another
Changed GridNavigator to derive from GameScript
Removed unnecessary message handling from grid components
Merge pull request #26 from VajraFramework/gridcollision

Gridcollision