Add Resistance Armor Modules, or at least support for mods

[Peter34]

It should be possible to fit modules into one's Modular/Power Armor that increase existing Resistances or give new ones. For instance I might want an Air Filtration Module that gives some Poison Resistance (since Poison often happens in the form of gas). Even if the devs don't intend to add such modules in the vanilla game, the game's structure should contain support for them so that modders can add them.

In addition to just having such Armor Modules as a possibility, for them to be a serious modding option the game needs to answer the questions of what happens if you fit 2 or more of the same kind of module?

I think a good solution is that all the Resistances from modules of the same kind should be sorted in order of numerical value, i.e. from highest to lowest. You get the full effect of the largest bonus, 25% effect of the 2nd largest, and 5% of all remaining ones. In this way, if vanilla Modules or modder-made Modules are properly conservative with how big Resistances Modules can grant, it can become close to impossible to achieve 100% Resistance, a.k.a. True Immunity.

Resistance Modules need to be able to use Power, although not all should (some Modules can represent metal plate or ceramic plate inserts, which obviously shouldn't draw electrical power), and it would probably also be a good idea to enable the flagging of Modules as Unique, meaning that that Module subverts the stacking rules and instead only gives the wearer the highest bonus and ignores all others of that type