remove combined {models,sprites}.mat, remove extra .mdl .spr exts

valve/pbr/models/headcrab.mdl/headcrab.mat

@@ -0,0 +1,40 @@
+
+{
+"for" "#models/headcrab/bottom.mdl"
+//"basecolor_map" "bottom.png"
+//"normal_map" "bottom_normal.png"
+//"metal_map" "bottom_metal.png"
+//"roughness_map" "bottom_roughness.png"
+}
+
+{
+"for" "#models/headcrab/butt.mdl"
+//"basecolor_map" "butt.png"
+//"normal_map" "butt_normal.png"
+//"metal_map" "butt_metal.png"
+//"roughness_map" "butt_roughness.png"
+}
+
+{
+"for" "#models/headcrab/front.mdl"
+//"basecolor_map" "front.png"
+//"normal_map" "front_normal.png"
+//"metal_map" "front_metal.png"
+//"roughness_map" "front_roughness.png"
+}
+
+{
+"for" "#models/headcrab/lowerside.mdl"
+//"basecolor_map" "lowerside.png"
+//"normal_map" "lowerside_normal.png"
+//"metal_map" "lowerside_metal.png"
+//"roughness_map" "lowerside_roughness.png"
+}
+
+{
+"for" "#models/headcrab/transparent section.mdl"
+//"basecolor_map" "transparent section.png"
+//"normal_map" "transparent section_normal.png"
+//"metal_map" "transparent section_metal.png"
+//"roughness_map" "transparent section_roughness.png"
+}