What changed in EDuke32, build by build

Avoid calling dragpoint on invalid wall indexes in SE 20 code

Fix renderer menu option hiding logic

Fix sloped sprite shading preview in editor

Fix sloped sprites to once again take on ceiling/floor shade

Ensure some hardcoded switch behavior maintains applicability only to wall sprites, not sloped (floor), consistent with the rest of the code

Don't call pushmove from DamageObject if sprite has invalid sectnum

Remove chdir for artLoadFiles now that the engine has g_modDir

Add globalgameflag DUKE3D_NO_HARDCODED_FOGPALS, which prevents the game from automatically defining white, red, green, and blue fogpals in the first four adjacent empty palookup slots it finds.