Add support for PCORAW data

Fixes ticket #11503.
Update netCDF version to 4.3.19
Update NetCDFServiceImpl and HDF-based readers for netCDF 4.3.19

There are a number of differences in the group/attribute names and
values returned by 4.3.19 when compared with 4.0.x.  Some of the names
contain spaces instead of underscores and/or extra characters; for image
data arrays, the endianness may be reversed (which was actually a bug in
4.0.x).

This completes ticket #6853.
Fix NetCDFServiceTest to account for 4.3.19 upgrade
Add Unidata Maven repository and fix the committed netCDF jar

netCDF 4.3.19 is not in Maven central, so the Unidata is used instead.
merge develop -D org -I include -E exclude: PR 528 (Tile performance improvements for VMS and NDPI)
merge develop -D org -I include -E exclude: PR 767 (Fix Channel.Color interpretation in ImageJ)
merge develop -D org -I include -E exclude: PR 775 (Add JWlz to Ivy dependencies)
merge develop -D org -I include -E exclude: PR 783 (Leica LIF: do not set the 'rgb' flag for 16-bit multi-channel data)
merge develop -D org -I include -E exclude: PR 788 (Do not prompt to update to the latest stable version if Fiji is used)
merge develop -D org -I include -E exclude: PR 790 (Update netCDF to 4.3.19)
merge develop -D org -I include -E exclude: PR 791 (Add support for PCORAW data)