Fix Flung Spheres not using the Blue Sphere collection effect

See merge request STJr/SRB2!1995

Fix Camera Interpolation Never Being Reset (Resolves #1026 and #976)

Closes #976 and #1026

See merge request STJr/SRB2!2008

Fix IPv6

See merge request STJr/SRB2!1612

Interpolate Shadows when Scaling Mobjs

See merge request STJr/SRB2!1986

Refactor P_CheckSector

Closes #870

See merge request STJr/SRB2!1946

Rewrite F_SkyScroll to fix overflows

Closes #1008

See merge request STJr/SRB2!1985

Hannu's "LUA_EnumLib optimizations for constant value access" with fixed merge conflict

See merge request STJr/SRB2!2017

[SUGOI] Multiplayer emblems

See merge request STJr/SRB2!1756

Port increment_move radius clamps from Ring Racers

See merge request STJr/SRB2!2013

Add HUD icons for timed NiGHTS powerups

See merge request STJr/SRB2!1949

Small text colormap tweaks

See merge request !1971

Fixes inconsistencies with thin players, like with Liftoff Gantry's scale section, and with large characters colliding with steep slopes instead of going up them.

Noticed some oddities with D_MapChange here with very rarely not changing player position when the map is loaded.

Don't give completion emblems when getting a game over in multiplayer (or any other kind of level reset)

Previously, level select only appeared in the SP pause menu if you load a complete save file.

Now, entering the game through an Extras menu level select shows that level select. Simply makes it more convenient, as you don't need to exit to the main menu again whenever you want to get to another level from an unlocked level select.

Tested all ways you can start a new map from the menu that I can think of (New Save File, Complete Save File, Mid-game Save File, several different Level Select types, custom Warp, Record Attack, Marathon, Tutorial), and could not smuggle wrong level selects into any.

This makes it consistent with SP's pause menu order. (Although admittedly I prefer how the other order looks.)

(Maybe some day...)