5.7.9beta45

FNV files: The fast navigation or *.fnv files are created as ancillary files
allowing navigation to be read without reading the full swath files. The *.fnv
files are in the MBF_MBPRONAV (166) format. Format 166 has always supported
comment records as lines beginning with the '#' character, but fnv files have
always been created without any comment records. Many MB-System programs read
fnv files directly without using the MBF_MBPRONAV i/o module. Now all format
166 files will be written with a first record documenting the contents of the
file:
fprintf(mb_io_ptr->mbfp, "## "
"<longitude (deg)> <latitude (deg)> <heading (deg)> <speed (km/hr)> "
"<draft (m)> <roll (deg)> <pitch (deg)> <heave (m)> <portlon (deg)> "
"<portlat (deg)> <stbdlon (deg)> <stbdlat (deg)>\n");
whether they are written by the MBF_MBPRONAV i/o module or by functions in
applications like mbprocess or mbpreprocess. All instances reading these files
will ignore these file header records.

Mbgrdviz: augmented and corrected the headers of route and site files output by
mbgrdviz, better self documenting the formats of these files.

Mbnavadjust: Added ability to import a reference bathymetry grid that can be
used to define global ties. Also modified so that when the main display list mode
limits what is shown to "with selected survey" or other modifiers, these constraints
also limit what navigation is shown in the project visualization. So, if one selects
a survey and then sets the list mode to show only the selected survey, then the
visualization will also only display the navigation from that survey, the crossing
ties or global ties from that survey, and only allow picking on that survey's
navigation.

Mbareaclean: Fixed issue in which mbareaclean does not apply filters for files
without pre-existing *.esf files.

Mbbackangle: Plots of the backscatter vs grazing angle distribution are no longer
histogram equalized.

Mbprocess: Modified the threaded processing function process_file() so that each
instance carries a thread id that can be checked during debugging.