Fix some compilation warnings
Fix tests compilation
Enable snapshots and port connect on startup
vtl: overall export progress bar
vtl: remove obvious warning
ignore "external timecode is sync locked" for non timecode slaves.
make MIDI clock work once more: 
   * increase filter bandwith to make it sync faster
   * use transport_frame instead of audible_frame for calculating the loop error (thanks robin!)
   * reduce the deadzone to 0.1% (thanks robin)
midi_clock_slave.cc: report to ardour the delta that the loop sees (revert me if you object)
Make track header faders insensitive to vertical scroll-wheel events again.

This effectively reverts d235a27a, and restores the behaviour to that of
Ardour 2.
Merge branch 'patches' of https://github.com/jdekozak/ardour
Merge branch 'nsm' of https://github.com/royvegard/ardour
Fix display of Spectral Analysis when no tracks are selected.

Spectral Analysis now displays graphs for selected regions, even when there
are no tracks selected. Fixes #2226.
if auditioner connections are somehow wiped out in CONFIG/ardour.rc, treat them as if they are still "default"
mark the step entry dialog as a dialog even though it is an ArdourWindow, to help with WM layering issues
add -L to curl in linux build script so that 301 responses while fetching harvid are handled
do not include harvid by default in linux build (wrong variable definition)
Merge branch 'master' of git.ardour.org:ardour/ardour
fix up export formats search path to correctly locate bundled (or installed) export formats
fix reload of Generic MIDI binding state when the target state involves just a binding map, with no specific controller bindings at all (should fix #5210)
add pkg-config check on liblo, now that NSM support requires 0.26 rather than just "any" version (fixes #5435)