DRO2IMF - Convert DOSBox OPL captures to id Software Music Format

IMF songs are used in many Apogee games, from Commander Keen to Duke
Nukem II.  There is also a converter available to convert IMF files into
MIDI files.

Written by malvineous()shikadi.net in June 2007, in a mishmash of rather
messy C/C++.  Feel free to do what you want with this code, but if you
make use of it please give credit where credit is due :-)