also run for extended periods of time.

For some reason, GUI operations which run for extended periods of time
may cause the engine to crash with a SIGHUP error on Linux. Apparently
this is caused by the watchdog bailing out and taking the engine with
it. This affects the new print operation as well as the existing message
operation in the file menu, possibly also search index generation for
the help browser, and maybe some other operations that still need to be
identified.

The new gui-busy method lets the GUI set an internal flag in the engine
which makes the engine keep the watchdog happy while the GUI does its
thing, using the same mechanism that is already in place to ping the
watchdog when running GUI-less. To these ends, the GUI needs to invoke
"pd gui-busy 1" when starting the time-consuming operation, and "pd
gui-busy 0" when the operation is done.

Massaged the routine a bit to bring it more in line with what vanilla
currently has, and backported some recent changes in rev. 1f383be3 and
rev. ff9e52c6 from vanilla which are supposed to fix some bugs in
sys_domicrosleep.

Sam Thursfield authored 4 years ago and Albert Gräf committed 4 years ago

This causes tar_em_up.sh to download an older version of nw.js suitable
for OSX 10.8.

It was accidentally removed by me in 4bffb36f.

Disable zexy/lpt on Windows for now, it doesn't work there at present and causes a segfault in the regression tests.

This adds support for the SMMF MIDI message format,
cf. https://bitbucket.org/agraef/pd-smmf.

It also adds canvas/path search for soundfont files, so that these can
be found more easily without having to use absolute pathnames, as well
as a few cosmetic changes to help and error messages.

In default "legacy" mode, the object is 100% backwards-compatible
(except for the soundfont file search), so that existing patches will
continue to work without any changes.

In SMMF mode, which is invoked with the new -smmf option (used either as
a creation argument, or with the "init" message), the SMMF message
format can be used to denote MIDI messages. Legacy messages still
continue to work in SMMF mode as well, except the "note" and "bend"
messages which are used in both formats with the same argument count but
different argument order. However, the corresponding shortcuts "n" and
"b" of the legacy format still work even in SMMF mode.

Rationale: SMMF offers the following advantages over the legacy message
interface that fluid~ currently uses:

- It covers all MIDI voice messages, as well as system exclusive
  messages. (Note that sysex support is particularly interesting in the
  context of fluidsynth because it allows to pass tuning data using
  sysex messages following the MIDI Tuning Standard (MTS), which
  fluidsynth readily supports.)

- It enforces a close 1-1 correspondence between the Pd MIDI objects and
  the message format (it uses the same basenames as message selectors,
  and has the arguments in the right order to easily interface with the
  Pd MIDI objects).

- It is is readily supported by some helper abstractions (midi-input.pd
  and midi-output.pd, available at https://bitbucket.org/agraef/pd-smmf).

- Last but not least, it is compatible with pd-faust and pd-faustgen2
  which makes it very easy to integrate Faust- and soundfont-based
  synthesis in Pd.