Fix loading of new HMD models and re-introduce HasMaterialFlags for compat with existing HMD models

hxd/fmt/hmd/Data.hx

@@ -40,6 +40,7 @@ typedef Index<T> = Int;
 
 enum Property<T> {
 	CameraFOVY( v : Float ) : Property<Float>;
+	Unused_HasMaterialFlags; // TODO: Removing this will offset property indices
 	HasExtraTextures;
 }
 

hxd/fmt/hmd/Reader.hx

@@ -17,6 +17,8 @@ class Reader {
 		switch( i.readByte() ) {
 		case 0:
 			return CameraFOVY(i.readFloat());
+		case 1:
+			throw "Obsolete HasMaterialFlags";
 		case 2:
 			return HasExtraTextures;
 		case unk:

hxd/fmt/hmd/Writer.hx

@@ -15,6 +15,7 @@ class Writer {
 		switch( p ) {
 		case CameraFOVY(v):
 			out.writeFloat(v);
+		case Unused_HasMaterialFlags:
 		case HasExtraTextures:
 		}
 	}