Add math.IsNearlyZero() and math.IsNearlyEqual()

[xCynDev]

These simple functions should be used when comparing numbers instead of ==, since floating point precision issues easily arise.
Felt like making them since someone on the Garry's Mod Discord server was confused as to why the following didn't work:

So now, you can use math.IsNearlyEqual() or math.IsNearlyZero() which solves the issue:

The functions allow you to give them a tolerance of your choice, but they'll default to math.exp( -8 ) otherwise.

Additional reason why the function is needed:

It's more visible when you display the decimal values.

[CornerPin]

• I think math.IsNearlyEqual should be renamed to math.IsEqualTol for consistency because we already have methods like Angle:IsEqualTol and Vector:IsEqualTol. Similarly, math.IsNearlyZero can be renamed to math.IsEqualZeroTol.
• An epsilon of $e^{-8}$ seems arbitrary to me, did you mean to set it to 1e-8 instead?

[xCynDev]

• I think math.IsNearlyEqual should be renamed to math.IsEqualTol for consistency because we already have methods like Angle:IsEqualTol and Vector:IsEqualTol. Similarly, math.IsNearlyZero can be renamed to math.IsEqualZeroTol.

Wouldn't be against it. In my opinion, IsNearlyEqual is more readable than IsEqualTol, I would keep it that way if it isn't going to prevent it from being merged as it won't affect new or old code.

Especially since IsEqualTol() looks like IsEqualTo() at a glance and could be confusing.

• An epsilon of $e^{-8}$ seems arbitrary to me, did you mean to set it to 1e-8 instead?

Yep! TIL Lua supports 1e-8 as a constant, I'll fix that in a bit.

[robotboy655]

Fixes Facepunch/garrysmod-requests#1991