Granger should be able to evolve into advanced granger if not stage 1. Fix this.
Fix a bug that allowed aliens to heal on the medistation.
Fix a potential crash if the target of a medistation is set to a non-client by a third party.
Prevent a possible overflow and divion by zero in G_ReplenishAlienHealth. A minimum heal rate of 10% will be kept.

The overflow might have caused a bug where aliens spontaneously healed at a very fast rate.
Merge branch 'gameplay/viech' into bots+viech