A few modifications:

1) Simplify REFRESH register handling via bit fields.
2) Use static methods in the Z80 emulator, if at all possible
3) Use a decoded opcode lookup, rather than decoding per instruction

Signed-off-by: Adrian.Conlon <adrian.conlon@gmail.com>

Z80/src/Disassembler.cpp

@@ -31,7 +31,7 @@ std::string EightBit::Disassembler::state(Z80& cpu) {
 	auto l = cpu.L();
 
 	auto i = cpu.IV();
-	auto r = cpu.REFRESH();
+	auto r = cpu.REFRESH().asUint8();
 
 	auto im = cpu.IM();