For old savegames, we now use a "dummy" iMUSE objet to skip the old
iMUSE save state. I had hoped to be able to do this without making
any changes to the iMUSE code itself, but I was unable to.
Also added note about how the save state for the new music will not
quite work if the mixer output rate changes. Personally, I'm not
too worried about that. It breaks, but it shouldn't break badly.
Albeit the code is marked as a hack inside the source, the original behaved
exaclty the same. If the code is removed the PC Speaker output will miss notes,
since unlike the original we only output to parts, which have an instrument set
up.
* IMuse is no longer a concurrency front-end.
* IMuseInternal now derives from IMuse.
* Common::StackLock used to protect thread-sensitive interface methods (same as IMuseDigital).
* clear_queue() included in stopAllSounds() so it can be removed from the public interface.
* Game ID now specified at init using property().
* Timer callbacks receive a struct containing IMuseInternal and MidiDriver refs, instead of just the latter.
* OSystem pointer from init is now cached and used instead of global.
All references to the g_system and g_scumm globals are now gone. BOOYAH!
Tested with MI2, DOTT and S&M, under Windows, in Native MIDI, Adlib, and Mixed modes. No regressions or concurrency issues observed. Manifestations of the latter are the biggest concern at this point.
svn-id: r21104
