fix conflicts after merge with master

diff --cc gtk2_ardour/ardour_ui.cc
Simple merge

diff --cc gtk2_ardour/ardour_ui.h
Simple merge

diff --cc gtk2_ardour/engine_dialog.cc
Simple merge

diff --cc gtk2_ardour/gain_meter.cc
Simple merge

diff --cc gtk2_ardour/port_group.cc
Simple merge

diff --cc gtk2_ardour/rc_option_editor.cc
Simple merge

diff --cc gtk2_ardour/route_params_ui.cc
Simple merge

diff --cc gtk2_ardour/route_ui.cc
Simple merge

diff --cc gtk2_ardour/utils.cc
Simple merge

diff --cc libs/ardour/ardour/audio_diskstream.h
Simple merge

diff --cc libs/ardour/ardour/session.h
Simple merge

diff --cc libs/ardour/ardour/types.h
Simple merge

diff --cc libs/ardour/audio_diskstream.cc
Simple merge

diff --cc libs/ardour/capturing_processor.cc
Simple merge

diff --cc libs/ardour/internal_send.cc
Simple merge

diff --cc libs/ardour/lv2_plugin.cc
Simple merge

diff --cc libs/ardour/midi_diskstream.cc
Simple merge

diff --cc libs/ardour/port_insert.cc
Simple merge

diff --cc libs/ardour/route.cc
Simple merge

diff --cc libs/ardour/session.cc
Simple merge

diff --cc libs/ardour/session_ltc.cc
Simple merge

diff --cc libs/ardour/session_transport.cc
Simple merge