Multi-track MIDI files are played back using separate callback chains
for each track, and this introduces the possibility of one track
becoming out of sync with the others. This was noticeable in WADs
that use multi-track MIDIs, such as Alien Vendetta. Increase the
timing resolution to microsecond precision to fix this.
When the tempo is changed, the times on all active timers must be
adjusted to match the new timing values. Add an API to do this and
invoke it when a tempo change meta event is read.
This change rewrites and simplifies the copyright headers at the top
of all source files:
* Remove "Emacs style mode select" line; this line was included in
the headers for the originally released source files and appears
to be to set the file type for old versions of Emacs. I'm not sure
entirely why it was required but I don't think it is any more.
* Remove "You should have received a copy of..." text from copyright
header. This refers to the old 59 Temple Place address where the
FSF headquarters used to be located and is no longer correct.
Rather than change to the new address, just remove the paragraph
as it is superfluous anyway. This fixes#311.
* Remove ---- separator lines so that the file headers are barer
and more simplified.
