Add Nuked OPL3 emulator v1.8

Set oplemu to nuked in config file. Also set oplrate and mixer rate
to 49716 for best sound quality.

Changelog for v1.8:

- New envelope generator.
- Rhythm mode emulation is 100% correct now.

Vogons thread: https://www.vogons.org/viewtopic.php?f=9&t=37782

Imported-from: https://www.vogons.org/viewtopic.php?p=661417#p661417

src/hardware/adlib.cpp

@@ -27,6 +27,7 @@
 #include "mapper.h"
 #include "mem.h"
 #include "dbopl.h"
+#include "nukedopl.h"
 
 #include "mame/emu.h"
 #include "mame/fmopl.h"
@@ -164,6 +165,42 @@ struct Handler : public Adlib::Handler {
 
 }
 
+namespace NukedOPL {
+struct Handler : public Adlib::Handler {
+	opl3_chip chip;
+	Bit8u newm;
+	virtual void WriteReg( Bit32u reg, Bit8u val ) {
+		OPL3_WriteRegBuffered(&chip, (Bit16u)reg, val);
+		if (reg == 0x105)
+			newm = reg & 0x01;
+	}
+	virtual Bit32u WriteAddr( Bit32u port, Bit8u val ) {
+		Bit16u addr;
+		addr = val;
+		if ((port & 2) && (addr == 0x05 || newm)) {
+			addr |= 0x100;
+		}
+		return addr;
+	}
+	virtual void Generate( MixerChannel* chan, Bitu samples ) {
+		Bit16s buf[1024*2];
+		while( samples > 0 ) {
+			Bitu todo = samples > 1024 ? 1024 : samples;
+			samples -= todo;
+			OPL3_GenerateStream(&chip, buf, todo);
+			chan->AddSamples_s16( todo, buf );
+		}
+	}
+	virtual void Init( Bitu rate ) {
+		newm = 0;
+		OPL3_Reset(&chip, rate);
+	}
+	~Handler() {
+	}
+};
+
+}
+
 
 
 #define RAW_SIZE 1024
@@ -806,6 +843,9 @@ Module::Module(Section *configuration)
 		else {
 			handler = new MAMEOPL3::Handler();
 		}
+	}
+	else if (oplemu == "nuked") {
+		handler = new NukedOPL::Handler();
 	} else {
 		handler = new DBOPL::Handler();
 	}