Bumped version to 2.4.9

See merge request !79

Bugfix: now loading across greenwich should work fine.

See merge request !78

Develop bugfixes 2.4.7 a

Contains two bugfixes:
- Wrong loading longitudes across greenwich
- Wrong report of loaded /not loaded files.

See merge request !77

Bumped version to 2.4.7 and documentation enhancements.

See merge request !76

Develop thredds subsetting

This branch contains developments for making the most of THREDDS subsetting capabilities exploited via "ncdf4"'s ncvar_get() and its parameters 'start' and 'count'.

See merge request !62

Started huge changes to get rid of dataset storage formats and grids. Almost all done but still not working. Must polish and debug.