Merge pull request GPSBabel#374 from tsteven4/jeepswarn

Fix g++-8 warnings in jeeps.

Track filter fix (GPSBabel#363)

* Fix compatibility for track filter GUI<->CLI.

Add a week unit for the track filter move option,
in addition to the existing day, hour, minute and second units.

Allow combination of units for track filter move option, e.g.
1w2d3h4m-5s = 1 week + 2 days + 3 hours + 4 minutes - 5 seconds.
This matches historical use, and is expected by the GUI.

Add the week unit to the GUI track filter ui.

Change the limits on the track filter move specs:
week: +/-10000 (unit didn't exit before)
day,hour,minute,second: +/- 100000 (+/-2000 for day before, +/-100 on others).

This resolves GPSBabel#357.
This resolves GPSBabel#358.

* add documentation for track filter move option.

Merge pull request GPSBabel#346 from tsteven4/r160

Roll version number for release 1.6.0.

Release 1.5.2.

GPSBabel 1.5.0 release.

Bump for 0302 release.

A bouncing baby babel beta is born.