* Move dssi_example_host out of examples and rename it to jack-dssi-host.
Change it from public domain to BSD-licensed.
* Add jitter-prevention logic to jack-dssi-host (timestamping events on
arrival and using the DSSI frame offset).
* Make jack-dssi-host deactivate a plugin when its GUI exits, and exit
when all GUIs have exited (valid behaviour for this host, as we start
the GUI automatically on startup and we have no way to restart it)
* Permit use of symbolic links to tell jack-dssi-host to start a particular
plugin automatically via argv
* Tidy up the build & install procedure a bit (still no configure though),
and make jack-dssi-host Usage report a bit more helpful
* Make fluidsynth-dssi install an extra symbolic link from
$PREFIX/bin/fluidsynth-dssi to $PREFIX/bin/jack-dssi-host to take
advantage of automatic startup feature