Customizable HP Gain Rate

I feel like building HP is a horribly boring and slow grind, and this
would allow the admins to increase the rate.
I personally would go with 3 as the multiplier.
Hp based gain mult scaling
Changed var name

And formatting changes
Default no change
Removed HP scaling, plain multiplier

bounded it to 1-100 so it isn't set to 0 by accident and stops gains.
Merge pull request #46 from Koveras/CustomizableHPGainRate

Customizable HP Gain Rate