Shader code cleanup

See merge request STJr/SRB2!1103

I am going to die :D (closes #337)

Closes #337

See merge request STJr/SRB2!1183

Fix clients being able to skip credits AGAIN (closes #339)

Closes #339

See merge request STJr/SRB2!1182

A special stage is a special stage, even outside of coop.

Closes #211

See merge request STJr/SRB2!1180

Don't count demo playback as visiting a level.

Closes #327 and #340

See merge request STJr/SRB2!1177

Add `-splitscreen` commandline parameter

See merge request STJr/SRB2!1175

Add P_CeilingzAtPos function

See merge request STJr/SRB2!1164

serverrunning means that you are actually the server.

Replace cvar initializers with a macro

See merge request STJr/SRB2!1178

Provide a default exe manifest

See merge request STJr/SRB2!1174

Fix some theoretical crashes when using the P_*XYMovement, P_*ZMovement, and P_RailThinker functions in Lua.

See merge request STJr/SRB2!1173

Add error message when the GDI Generic OpenGL renderer is encountered in Windows

See merge request STJr/SRB2!1172

Expose MODVERSION to Lua (because for some reason it wasn't).

See merge request STJr/SRB2!1158

Updated 16 bit momentum values to 32 bit in demos, changed demo version

See merge request STJr/SRB2!1157

Support sectors as sound origins in Lua

See merge request STJr/SRB2!1144

Autocomplete aliases in console

See merge request STJr/SRB2!1113

Expose V_GetStringColormap to Lua via v.getStringColormap().

See merge request STJr/SRB2!1111

Chain Homing with Attraction Shield

See merge request STJr/SRB2!1109

PlayerCmd Port

See merge request STJr/SRB2!1072

Fix some theoretical crashes when using the P_*XYMovement, P_*ZMovement, and P_RailThinker functions.

2.2.8 prep

See merge request STJr/SRB2!1170

Fix uninitialized variable issue in patches with missing grAb chunks

See merge request STJr/SRB2!1171

Prevent Canarivore gas from teleporting up walls

See merge request STJr/SRB2!1154

Fix #178

Closes #178

See merge request STJr/SRB2!1112

Remove "The OpenGL renderer is incomplete" notice (closes #281)

Closes #281

See merge request STJr/SRB2!1169

Fix graphics replacements not taking effect via -file

See merge request STJr/SRB2!1168