Changes for version 0.84
- Added PREREQ_PM for PDL version 2.2 or later to satisfy CPANPLUS email.
- Changed barfs to croaks--give error info from point of view of caller
- Fixed two bugs in getdimensionnames and gettext: Failed to check existance of $self->{VARIDS}{$varnm} before making netcdf library call.
- Changed 'fast' option on new() to the more general {TEMPLATE => } option.
- Added options for compression and decompression of netCDF files to/from PDLs. Uses (mostly) standard netCDF offset/multiplier compression.