Engine/Duke32: Some cleanup
- Remove unused function "A_DoGutsDir()".
- Replace negative tilenum check in Proj_MaybeSpawn() that was only used for SMALLSMOKE. Now uses two separate functions.
- Fix wrong parameter name in polymost_drawtilescreen() (wallnum -> tilenum)
- Fix check_sprite() in engine.cpp printing the sectnum instead of the picnum.
- Make fadepal(), G_FadePalette(), etc. use unsigned 8 bit parameters instead of signed 32 bit integers, to match videoFadePalette().
- Make cstat parameter 16 bit in classicDrawVoxel().