RA sequence cleanups.

Note: Removing Length: * from interior boxes and larvae as well as barrels
is intentional, boxes have just 1 frame, and frames 2+3 of larvae and
barrels are just duplicates of the first, added by Westwood to work around
damage stage issues.

Fixes fence palette on desert maps.

mods/ra/rules/defaults.yaml

@@ -471,11 +471,11 @@
 	TargetableBuilding:
 		TargetTypes: Ground, DetonateAttack
 	RenderBuildingWall:
-		Palette: terrain
+		Palette: effect
 	GivesExperience:
 	EditorAppearance:
 		RelativeToTopLeft: true
-		UseTerrainPalette: true
+		UseTerrainPalette: false
 	AutoTargetIgnore:
 	ProximityCaptor:
 		Types: Wall