support importing OPL musical instruments about opn2bankeditor

[freq-mod]

OPL and OPN chips don't have that much in common. Register maps aren't compatible at all, parameters have different bit depth (AR on OPL3 has 0-15 values, AR on OPN2 has 0-31 for example) and a lot of other caveats. So, I heavily doubt it's possible

[freq-mod]

Ah, I forgot. ADSR differs so wildly between these two chip families, (sustain, decay, rate scale level) instrument after import would be a total mess. The same applies to OPN -> OPL, since OPL doesn't have secondary Decay.

[denjhang]

@freq-mod In fact, there is a conversion program to realize the conversion from OPL VGM to OPN VGM. Please refer to this project https://github.com/digital-sound-antiques/vgm-conv
I tried many OPL VGM files, which can be converted to OPN normally without exception.

[Wohlstand]

Closing as abandoned.