Proper reset functions for OPL3 and OPL3Duo. If there would've been no hard reset then all registers of channels 9 .. 17 would not be cleared due to the chips operating in OPL2 mode. The shadow register do not yet take into account OPL2 vs OPL3 mode!
PlayNote will only reset the KEY-ON if it is set. This was giving some glitches with some of the drum sounds,
Enabling all 4-op channels will now set register 0x104 once instead of multiple writes for each 4-op channel.
Added enable all 4-op channels functions for opl3Duo.
Added an option to debug the data written to the board by defining OPL_SERIAL_DEBUG in opl2.h