Re-enable MT-32 emulation midi device

[acidbee]

Fixes #27
Re-enabled the mt32 midi device option.

[acidbee]

Should be noted that I have been having troubles launching nDOS via .idos packages in the process of getting this working. I think this might be my environment/device as after switching back to master, I was still having issues with it. It was working just fine before I started tinkering and I'm not sure how the changes would impact that. Launches just find normally, but nevertheless, worth testing before merging.

[nturley3]

Taking a look at this. Definitely looks like I removed it from the code by accident in a previous dosbox SVN merge. Would you have a good test case I can try when I get this working?

[acidbee]

Sorry, I checked this frequently after I submitted the pull request, but tapered off since then.

The simplest test case I can think of, is you should be able to set you mididevice setting to mt32 and the console output won't complain about that not being a valid setting.

For an applicable test you can actually hear, you'll need to grab a copy of the MT-32 ROMs. I think you can find a site hosting them here. I put them in the config directory.

Then I followed the setup instructions found here on dosbox-x's wiki. Below is a copy of the midi settings I used in my dospad.cfg file and note the mt32.romdir is set to config.

[midi]
mpu401=intelligent
mididevice=mt32
mt32.romdir=config
mt32.reverse.stereo=false
mt32.verbose=false
mt32.thread=true
mt32.chunk=16
mt32.prebuffer=32
mt32.partials=32
mt32.dac=0
mt32.analog=2
mt32.reverb.mode=auto
mt32.reverb.time=5
mt32.reverb.level=3

Lastly, I recommend testing it with a game that supports mt-32 sound. My personal preference is Space Quest I (1991 VGA remake) as the differences are night and day and immediately apparent.