MIDI docs: use getPorts()

Also use boolean to control synth start and stop.
Add mention of feature declaration in Manifest.
Add virtual MIDI devices to bullet list.

Change-Id: I7b36e3ce69caf9d1d15d23f1a0836d525022ef9e
Signed-off-by: Phil Burk <philburk@google.com>
1 file changed