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

valve/pbr/models/w_shotbox.mdl/w_shotbox.mat

@@ -0,0 +1,32 @@
+
+{
+"for" "#models/w_shotbox/box.mdl"
+//"basecolor_map" "box.png"
+//"normal_map" "box_normal.png"
+//"metal_map" "box_metal.png"
+//"roughness_map" "box_roughness.png"
+}
+
+{
+"for" "#models/w_shotbox/boxside.mdl"
+//"basecolor_map" "boxside.png"
+//"normal_map" "boxside_normal.png"
+//"metal_map" "boxside_metal.png"
+//"roughness_map" "boxside_roughness.png"
+}
+
+{
+"for" "#models/w_shotbox/shell.mdl"
+//"basecolor_map" "shell.png"
+//"normal_map" "shell_normal.png"
+//"metal_map" "shell_metal.png"
+//"roughness_map" "shell_roughness.png"
+}
+
+{
+"for" "#models/w_shotbox/topbox_shell.mdl"
+//"basecolor_map" "topbox_shell.png"
+//"normal_map" "topbox_shell_normal.png"
+//"metal_map" "topbox_shell_metal.png"
+//"roughness_map" "topbox_shell_roughness.png"
+}