Added RF_ABSOLUTEOFFSETS and RF_FLIPOFFSETS

Adjust the sort scale of splats
Do splat sorting in R_CreateDrawNodes if either vissprite is a splat, instead of if both are

Fix papersprite scaling with spritexscale and spriteyscale in Software

- Added render flags (see r_defs.h)
- Implemented floor splats
- Drop shadow sprite rendering through render flags

Simplify rotation code when the pivot isn't in the center

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 !1171