[Draft] Customizing power output decrement when a power plant is damaged

[Coronia]

This implementation worked in practice, but not sure if it's the proper approach. Also there might be missing check and cases, and its interaction with Drain (especially Ares's new options) still remains a question. For now I'd pull it as a draft to get some advice and testing. If anyone finds problem or has better idea please make me know, thank you very much.

• It is possible to customize the power decrement of a power plant when it's damaged. The actual power output for this plant will be: Power minuses the product of original power decrement and Powerplant.DamageFactor. Can't reduce power output lower than 0.
  • Specifically, if the factor is set to 0.0, power output won't be decreased by losing health for this power plant.

In rulesmd.ini:

[SOMEBUILDING]                     ; BuildingType
PowerPlant.DamageFactor=1.0        ; floating point value

[mevitar]

There was already an attempt to make power not degrade with powerplant's damage, in #550 (but that one seems to be abandoned and this one is more customizable).

I think it would be better if the tag name was something like Power.DamageFactor= (or even PoweredSpecial.DamageFactor=, but this one is pretty long).

[tyuah8]

Unless I am not understanding something, how come we can't just hook at 0x44E861 inside BuildingClass::GetPowerOutput() and change the call to GetHealthPercentage() to something else? It is how the game now, even with Ares, is handling power loss on power plant damage.