Disable renderhitbox in multiplayer altogether

See merge request STJr/SRB2!2142

Fix floorsprite rendering with 1x1 images

Closes #1052

See merge request !2141

Replace CV_NETVAR with CV_NOTINNET for cv_renderhitbox (Fixes #1103)

Closes #1103

See merge request !2140

Expose skin.supername to Lua

See merge request !2138

Optimize sprite rendering by ignoring completely occluded sprites

See merge request !2131

Interpolate Hitboxes when Scaling Mobjs

See merge request !2124

The CV_NETVAR flag being used for cvars not registered in a dedicated server context will completely mess with the internal netid to cvar linkage.
And I'm not really keen on registering a cvar purely for rendering on dedicated servers, so let's just prevent renderhitbox from being changed in netgames entirely.

Make camera noclip during NiGHTS gameplay

See merge request STJr/SRB2!2136

Fix possible crashes in the Lua API when accessing invalid fields

See merge request STJr/SRB2!2128

Allow input during title animation after the first time

See merge request !2122

Don't Copy mobj->dontdrawforviewmobj To MT_OVERLAYs

See merge request !2125

Don't attract bomb spheres with Nightopian Helper

See merge request !2135

Fix the Record Attack Background Jumping

See merge request !2129

Add toggle for instant retry in Record Attack

See merge request STJr/SRB2!2120

Make renderhitbox a netvar to prevent clientside wallhacking

See merge request STJr/SRB2!2133

Fix sprite scale column iteration crash

See merge request STJr/SRB2!2130

This has the effect of misrepresenting how many sprites are actually visible, but it's more "accurate".

- Tweaked Aether, Midnight and Volcanic
- Credit Chrispy & Saneko for new skincolors