Army movement update +bugfixes.

Hi everyone, I made some changes to the pathfinding which especially affects huge armies.
Armies stick to the correct formation far better and form a correct formation no matter its size. Their movement around obstacles is also improved.

Other fixes included in this patch:
- Fixed buttons from overlapping in niche situations.
- Fixed an error when pausing while placing troops in the Testing Grounds.
- Fixed an issue where you couldn't beat mission one when clearing the nomads with non-hero troops.
- Buildings were incorrectly targeting flying troops.
- Fixed mortars load animation.
- AI now sends neutral crossbowman from the crossbowcamp (Battle mode, King of the Hill map) to attack now and then.