add export visibility control to libpbd (works thus far on linux/gcc)
make small beginning on visibility control in libardour
add defines to gtk ardour build so that it knows that our internal libs are all shared
new file for libmidi++ export control
add export visibility macros across libardour
remove some unnecessary export macro placements
export-ify libmidipp
remove a few more misplaced export macros
add export control to libevoral
add export control to libgtkmm2ext
add new visibility macro headers omitted from previous commits
get everything compiling with libardour built using -fvisibility=hidden
add export control to control protocol library
mark more functions for export (ardour runs now)
include (probably) necessary stuff in panner compilation flags
tweak up DLL=1 defs for control surfaces
add -fvisibility=hidden to libpbd, and make things work
add -fvisibility=hidden to libgtkmm2ext, and make things work
add -fvisibility=hidden to evoral, and make things work
add -fvisibility=hidden to libmidi++ and make things work