Implement the interface PerformanceSettings

[Bagellll]

Hello yet again,

As per #93 I have fixed the initial issue with the interface returning incorrect values but tried to go and make it work best I could for real rather than storing useless data as a patch. I asked Jorrit from the Jolt repo what out of the parameters was possible to implement and did so (which ended up only being the velocity related parameters). There are also inline functions for each parameter just in case they're ever needed again.

[misyltoad]

Maybe it would be better to just provide a simple stub that returns the default values the regular VPhysics exposes...?

Do we know of anything that relies on calling SetPerformanceSettings and values actually changing in the system?

[Bagellll]

That is what I did initially just for compatibility reasons. I probably should've made the PR then instead, I'll edit it now if you want.

When it comes to things relying on SetPerformanceSettings, if the scope of this project is outside just GMod (which has an api call for setting these details, I imagine someone or a mod needing it), there may be another sourcesdk project that would've relied on it. I'm just speculating but it seems reasonable.

But again, I'll push a commit to revert the functionality if you'd like. No biggie.

[misyltoad]

We can keep the PR around, but I would make one that just stubs it out for now, and we can come back to it if anything ends up depending on it.

[misyltoad]

You should do it with the values from regular VPhysics if you do stub it out, to keep behaviour consistent.

[Bagellll]

Before I added anything special it behaved just as intended, the values are set by the mod. Will do though, making a new PR.

[misyltoad]

I want to tag 0.11 today, so I may beat you to adding a stub here. :b

[Bagellll]

You did ;-;

[Bagellll]

That last commit was because I forgot to put the actual application of the settings behind the check too. Stylistic choice to guard at the beginning