Cis

Included in this release:
- Improved colocation and aggregation performance
- Moments kernel gives colocation and aggregation statistics
- More examples in documentation.
- Numerous bugfixes (see JIRA for full list).

Included in this release:
- New **Statistical comparison** command `cis stat` - produces detailed statistical output from comparing two compatible netCDF variables in the same or different files.
- New **Evaluate** command `cis eval` - allows evaluation of user provided expressions on compatible CIS datasets e.g. for averaging, quality control, interpolation...
- More multivariable support (for colocation and aggregation)
- Support for GASSP data
- Assorted bugfixes.

Contains new features and bug fixes including multivariable support for subsetting and aggregation.