Build 22: Overheating rework, Different Mechs to unlock

Build 22:

- Overheat is reworked a bit. It now won't go up if you're continuing shooting with overheated weapon set;

- Your first mech will now have a single weapon set with 5 slots and high overheat capacity so new players shouldn't bother with too much systems. ||We'll save most annoying mechanics for some "hard" mode Mechs||

- New different Mechs to buy;

- New buildings visuals;