Miscellaneous bug fixes

Fixed - Squads cannot move after taking a tower
Fixed - Units do not engage enemies if they are moving
Fixed - Swordsman are not spawning in the correct location
Fixed - Tower selector is shown after the tower is destroyed
Fixed - Game crash when mages engage in combat
Added virtual getter for Target Position

Allows objects to specify custom locations for enemies to attack.
Added borders
Experimenting with different unit masses
Added particle effect for Mage Ice Wand
Initial version of IceWand