Currently, Roland MT-32 sound is broken for
SAMNMAX. Just try the intro song with shut off
speech. It is very obvious that it plays with a quite
reduced number of channels compared to the
original interpreter.
Now, due to the not-so-helpful code design (much
of the iMuse code has been drawn into the common
code) it has become increasingly difficult to fix Midi
related thing in iMuse. I have added more and more
crude hacks over time.
SAMNMAX requires more elaborate channel
allocation. To make it happen I have added driver
wrappers for Midi to the iMuse code.
Other than that, I have done only minor cleanup here.
Actually, I would have liked to withdraw much more
of the iMuse code from the common code and move
it to SCUMM (basically all the MidiChannel
stuff which is exclusively used by iMuse. But it turns
out that it is so thoroughly intertwined (the major
blocker here being the AdLib driver) that it requires
more thought and effort and would just distract me
from fixing the SAMNMAX sound.
This in turn enables modifying MidiDriver_MPU401::close() to allow
it to be called on a midi driver that has not yet been opened.
The specific issue that triggered me to make these changes was a
crash-upon-quit in HUGO, caused by it instantiating a midi driver,
then encountering an error (missing hugo.dat) *before* having
opened the new midi driver; the general cleanup code then tries
to close the (not yet opened) midi driver -> kaboom
Also fixed some engines which were leaking MidiDriver instances.
