Rework the outline library and fix the outstanding issues with it (#1628)

Its finally here, the rework of the outline library which started
because of #1411
Ive spent quite some time on this trying over 50 different approaches,
running into various setbacks each time.
Some of them got solved:
Facepunch/garrysmod-issues#5744
And some didnt:
Facepunch/garrysmod-requests#2308

But this is what i consider the best thats possible in gmod today in
respect to functionality and performance.

This rework includes(i may have forgotten some, its been a while):
- A switch to using the zbuffer instead of line of sight checking every
single entity
- Outline thickness option
- Multiple render types for outlines
- More performant drawing
- Drawing not breaking when scopes are used in weapon addons
- Full documentation
- Fixed outlines being thinner on one side than the other

The comments in the code explain a lot so i hope those answer most
questions.

---------

Co-authored-by: Tim Goll <[email protected]>
Co-authored-by: Histalek <[email protected]>

Author: 3 people

CHANGELOG.md

@@ -16,6 +16,7 @@ All notable changes to TTT2 will be documented here. Inspired by [keep a changel
 - Added option to enable team name next to role name on the HUD (by @milkwxter)
 - Added score event for winning with configurable role parameter (by @MrXonte)
 - Added ExplosiveSphereDamage game effect for easy calculation of explosion damage through walls (by @MrXonte)
+- Added support for outlines of different thickness (by @Wardenpotato)
 
 ### Fixed
 
@@ -42,6 +43,8 @@ All notable changes to TTT2 will be documented here. Inspired by [keep a changel
 - Fixed issue in new Ammo dropping that could cause an error when dropping for modified weapon bases. (by @MrXonte)
 - Fixed C4 not showing the correct inflictor when the player is killed (by @TimGoll)
 - Fixed M16 Ironsight misalignment (by @SvveetMavis) 
+- Fixed outline interactions with certain weapon scopes (by @WardenPotato)
+- Fixed outlines not rendering uniformly (by @WardenPotato)
 
 ### Changed