Add support of RetroWave OPL3 hardware protocol

[ReimuNotMoe]

Add support of RetroWave OPL3 hardware protocol.

[ReimuNotMoe]

Resolves #190

[Wohlstand]

I'll review this once I get my home, on a first look, seems good. One note:
We don't use "Egyptian" brackets, so, please follow the code style of project:

if(condition)
{
    some();
}

[ReimuNotMoe]

I'll review this once I get my home, on a first look, seems good. One note: We don't use "Egyptian" brackets, so, please follow the code style of project:

if(condition)
{
    some();
}

The coding style is changed now.

[Wohlstand]

Looks fine to me. I think I'll tweak some other style cases by myself. I'll merge this.

[Wohlstand]

Sorry for the late reply, I was very tired and slept for a long time.

[ReimuNotMoe]

You're welcome. Take care.