Mercy changes (and others too) for S3

[GreyFalcon-11737]

@mercy1trick-1652

Damage boost- Now only boosts non-critical impact damage.

Sounds good to me.

@GreyFalcon-11737

OVERHAUL TO DAMAGE BOOST

1. Limit damage boosts to a maximum of 100% or 2x.
2. Turn Headshots into damage boosts.
3. Limit all Headshots to a maximum of 100% or 2x.
4. Adjust the affected Heroes.