- more options for Doom 64 style gradients on walls:

* Colors can npw be defined per sidedef, not only per sector.
* Gradients can be selectively disabled or vertically flipped per wall tier.
* Gradients can be clamped to their respective tier, i.e top and bottom of the tier, not the front sector defines where it starts.

The per-wall colors are implemented for hardware and softpoly renderer only, but not for the classic software renderer, because its code is far too scattered to do this efficiently.

src/p_saveg.cpp

@@ -105,6 +105,9 @@ FSerializer &Serialize(FSerializer &arc, const char *key, side_t::part &part, si
 			("yscale", part.yScale, def->yScale)
 			("texture", part.texture, def->texture)
 			("interpolation", part.interpolation)
+			("flags", part.flags, def->flags)
+			("color1", part.SpecialColors[0], def->SpecialColors[0])
+			("color2", part.SpecialColors[1], def->SpecialColors[1])
 			.EndObject();
 	}
 	return arc;