NOOP, re-indent, fix whitespace
revert parts of bf13bf63, change track-header color on selection
simplify time-axis packing: consistent table layout
remove (unused) separator, update TAV height calc.
update track-header width when track-number visibility is toggled
new min. height for midi controls
distinguish global peak-reset button from meters:

With > 2 channels, the editor toolbar meters are
otherwise very similar to the reset-button.
prepare for clang static analysis of RT-functions:

see: https://github.com/fundamental/stoat
eventually more functions should be annotated, and
a common header file should be used to
  #define REALTIME __attribute__((annotate("realtime")))
fix [potential] double clock connection:

ARDOUR_UI::set_session() starts clocking for a given session.
make sure ARDOUR_UI::parameter_changed() does not connect
before the session is active.
experiment with track-selection box shadow