Process muted tracks so that they can be unmuted instantaneously.

TODO:
1.  An envelope to smoothly fade the mutes/soloes
2.  A separate "power" button to shut down the track for real...
Add envelopes to the mute/solo functionality so that it will be smooth
and click-free...
Define the track types instead of referencing them as integer values
(hashtag:  ancient code cleanup)
In the unlikely event that an audio device requests a buffer size greater
than our max buffer size, print a warning and truncate.
(never actually encountered this, but it's a good idea anyway...)
Add a missing newline...
Half the size of each OSC buffer (still 3-4 times the largest message size
after profiling), and increase the buffer count to 256 from 64, as more
and more stuff is sent to the UI over OSC.
Optionally draw dB levels on a peak_meter...
Bump version number
Don't assume that folders will be less than 256 chars in length, use
1024, which nobody should ever be using more than...
(and if they do, "unsupported")...
Move the scheduler picking #ifdef after sched.h is included...
More work towards allowing multiple instruments and effects on the same
track...
Remove some really old and crufty commented-out code...
More work towards making the tracks into a single type that can run
chains of instruments and effects...
Even more refactoring to eliminate the concept of a track type...
Show the peak dB of each peak meter as a tooltip that can be reset with
a mouse click...
Replace calls to the deprecated map() built-in with list comprehensions...
Fix audio item glue being broken by the recent updates to the audio engine.
Fix a regression when the audio item indexes were added because the wrong
number was being indexed...  Caused audio items not to play at all, or
play on the wrong track maybe...