Also seek the extension ROM for the MSX 2.

Machines/Utility/ROMCatalogue.cpp

@@ -573,6 +573,7 @@ Description::Description(Name name) {
 		case Name::MSXDOS:			*this = Description(name, "MSX", "the MSX-DOS ROM", "disk.rom", 16*1024, 0x721f61dfu);				break;
 
 		case Name::MSX2GenericBIOS:	*this = Description(name, "MSX", "a generic MSX2 BIOS", "msx2.rom", 32*1024, 0x6cdaf3a5u);			break;
+		case Name::MSX2Extension:	x*this = Description(name, "MSX", "the MSX2 extension ROM", "msx2ext.rom", 16*1024, 0x66237ecfu);	break;
 
 		case Name::SinclairQLJS:
 			*this = Description(name, "SinclairQL", "the Sinclair QL 'JS' ROM", "js.rom", 48*1024, 0x0f95aab5u);

Machines/Utility/ROMCatalogue.hpp

@@ -118,6 +118,7 @@ enum Name {
 	MSXDOS,
 
 	MSX2GenericBIOS,
+	MSX2Extension,
 
 	// Oric.
 	OricColourROM,