"While 'atomic' has a volatile qualifier, this is a historical
artifact and the pointer passed to it should not be volatile."
Furthermore "It is very important that all accesses to a
particular integer or pointer be performed using only this API"
(from https://developer.gnome.org/glib/2.68/glib-Atomic-Operations.html)
Hence initialization of atomic variables is changed to also use
this API, instead of directly initializing the value.
This also fixes a few cases where atomic variables were
accessed directly.
see also libs/pbd/pbd/g_atomic_compat.h
To mitigate concurrent rendering, the waveform cache adds a random
range of pixels centered around the visible waveform.
Alignment is using integer half_width = width_samples / 2;
This always aligns the left-edge to the left-most cairo-pixel.
This fixes an issue with moving moiree patterns in waveforms when
zooming vertically (which invalidates the cache and uses a
different random number of pixels),
Generated by tools/f2s. Some hand-editing will be required in a few places to fix up comments related to timecode
and video in order to keep the legible
