Add per-lifeform sensitivity for aliens

[keatsandyeats]

Aliens can now have a different sensitivity for each lifeform by setting "Lifeform specific sensitivities" to "On" in the menu. Sensitivity sliders for skulk, gorge, lerk, fade, and onos will appear. This option is hidden if "Team specific sensitivities" is "Off".

Some notes:

• This PR introduces a parent-child option tree with three levels (for example sensitivity_perteam>sensitivity_perlifeform>sensitivity_skulk). Currently this means you can hide sensitivity_perteam, which will hide sensitivity_perlifeform appropriately, but sensitivity_skulk will still be displayed. Please see https://github.com/sclark39/NS2Plus/pull/55 for a method of addressing that.
• Enabling sensitivity_perlifeform overrides sensitivity_a, but sensitivity_a will still be displayed. It feels wrong to display an option that doesn't do anything, but I couldn't come up with a better solution. The tooltip for sensitivity_perlifeform mentions this behavior, at least.
• I used the LocalPlayerChanged hook to determine when to change sensitivity. According to a comment right below that, it doesn't always get called when changing teams. I never discovered the case where it doesn't get called, so I'm not sure if that's a problem here.

[Mendasp]

To solve the issue with displaying an option that's irrelevant you could make it a child of perlifeform sens and make it so it displays if the value is off.

I'm speaking from memory but I think that's an option and it'd solve the problem.

[keatsandyeats]

Thanks for the suggestion @Mendasp. The per-lifeform sens already has children that it hides when it's set to "Off" (namely, each individual lifeform's sens). I'm not sure if there exists a way to have different children for different hidevalues. So therefore I don't know how to also hide the alien team sensitivity when per-lifeform sens is "On".

[Mendasp]

Yeah, I was speaking from memory so I thought I already had some handling for it displaying when it's on/off (ie. show a set when it's on and another when it's off). You'd have to add something like that so you could maybe define a table of children depending on the hide value.