Halve Xenomorph Electrification Damage

Created by: dylanstrategie

It's currently ridiculously easy for Xenomorphs to shock themselves to death on station equipment, given that they get the same damage as humans do. I have halved it given that the alien's only way to entry into most places, outside of ventcrawling, is destroying shit

Also APCs do double electrocution damage due to them having two electrify wires, this balances that (otherwise slashing an APC on a station with normal power output is an instant crit)

New crit thresholds for aliens are 1 million W for the APC and 8 million W in general, both with 100 % electrify ratio

Fixes #4308 (closed) retroactively

Changelog included