5.7.6beta14

-----> 5.7.6beta14 (October 8, 2019)

MBnavadjustmerge: Added options --unset-short-section-ties=min_length and
--skip-short-section-crossings=min_length that allow the deletion or prevention
of ties made using short sections of data. This increases the reliability of the
autopicking of ties. The track length threshold is specified with the
command.

MBnavadjust: Restrict autopicking of ties incorporating short sections of data.
The track length threshold is 1/4 of the target segment track length specified
in the options dialog.

Format 88 (MBF_RESON7KR) and Format 89 (MBF_RESON7K3): Corrected handling of
reverse-mounted receive and/or transmit arrays.

MBpreprocess: Fixed handling of --filter-apply-nav option.

MBclean: Added flagging/unflagging by beam angle as part of the -Y option
-Yangle_left/angle_right/3 to flag outside angle_left to angle_right
-Yangle_left/angle_right/4 to unflag outside angle_left to angle_right

Terrain Aided Navigation (TRN) tools: The TRN related code has been refactored
and reorganized by Kent Headley. There are now three related directories under
src: src/mbtrn src/mbtrnav src/mbtrnutils. The former program mbtrnpreprocess
is now mbtrnpp. The source for mbtrnpp is now in src/mbtrnutils rather than
src/utilities.

Code stye: Kurt Schwehr is systematically altering the code to conform to best
practices regarding header inclusion and reduced variable scope, particularly
for loop indices.