Removed unit experience from GameState
Reduced weapon damage for low level units
Updated Medieval AI

Level 1 tuned for Melee tower level 1, Unit level 7
Level 2 tuned for All Towers level 1, Unit level 12
Updated Prehistoric AI

Tuned for no tower upgrades, troop level 10
Merge branch 'dev' of https://github.com/Chickenbottom/CSS385_PowerOverwhelming into dev