When RR73 is received we log the QSO, turn "Call 1st" OFF, and call CQ again.
Also, allow Alt+C and F6 (the latter only if altenrate F1-F6 bindings
are active) to toggle "Call 1st" ON/OFF.
Move to OnRowChange edit strategy for log tables so that deletes from
view can be implemented cleanly.
Improve layout of log view tables by resizing to contents.
This change incorporates a reorganization of the GUI code with
widgets, validators, models, and item delegates being moved to
sub-directories.
Relax the requirements of the ForeignKeyDelegate and related
CandidateKeyFilter classes to allow them to work with constant model
pointers for both referenced and referencing models.