Fix edit point selector on Mixbus.
Fix mismatched note resize drag cursor and behaviour.
Fix zoom out limiting logic to actually limit minimum zoom.
Fix incredibly unlikely NULL pointer dereference.
Fix Region::verify_length() so it actually does something.
Fix incredibly unlikely NULL pointer dereference.
Fix broken logic and possible NULL pointer dereference for Bundle XML.
Avoid potential division by zero.
Fix NULL pointer dereference on malformed Playlist XML.
Fix potential use of uninitialized value.
Gracefully avoid importing audio that somehow has 0 channels.
Remove unused variable and redundant arithmetic.
Constrain variable scopen and avoid uninitialized values existing at all.

Note: dead assignments trigger scan-build dead code warnings, which
initializations do not.
Clean up funny code and initialize variables.
Remove obviously dead/redundant code.
Avoid possible use of uninitialized values.

This could only happen with a broken widget, but it shuts up clang and doesn't
hurt.
Make MIDI channel selector rows/col constraints actually do something.

Seems kind of pointless since it's always 4 anyway, but whatever.