Previously this was inherited via PBD.
On MacOS/X, this adds
"-undefined dynamic_lookup -flat_namespace"
and various "-framework .." options to linkflags
Without this flag, .dylibs fail to link usually because
of missing `-lintl` (Undefined symbols: "_libintl_dgettext")
On other systems this is a NO-OP:
CFLAGS_OSX, CXXFLAGS_OSX and LINKFLAGS_OSX
are only set on the darwin platform.
uselib is no longer implicit (inherited by .use). This is still incomplete,
some uselibs for non-linux variants may be missing.
bld.is_defined("HAVE_XXX") also no longer works and will have to be
changed (I think to bld.env["HAVE_XXX"]) in countless places.
* allow to change buffersizes
* subscribe to buffersize & samplerate changes
* add support for half-duplex devices.
* aggregate Devices (not yet used) code from JACK2
* unify deprecated API wrappers
* properly keep track of MIDI ports
* disable MidiI/O during freewheeling
* various small fixes & cleanup
