Upgrade to 2.3.1

Upgraded documentation

Develop bugfixes 2.3.0

Configfile doc problems

Fixed problems with outdated configuration file documentation.

Develop update configfile doc

Documentation on configuration file has already been updated

Develop upgrade to 2.3.0

Documentation upgraded. Ready for internal release.

Documentation updated. Some bugfixes too. Working + tested (Virginie test scripts passed) version, could be released internally.

Develop bug load

This modification corrects a bug that appears when using observations only. Indeed, in that case, it is not possible to use the model mask for the observations since there is no model even if the user requested an interpolation. Therefore the condition nmod >= 1 should be tested whatever the user requests for output=lonlat/lat/lon (then an interpolation is needed) or the user requests explicitely for an interpolation. If nmod == 0, the observed mask would be used ( although a security test to check that this mask has indeed been provided could be good to add)

Develop fix acc doc

The documentation has been updated according to issue #16