...to reflect recent changes in ews-source-calc commit e162c48.

This reverts commit 1f935d5f.

- Individual grouping based on GroupBy content (defined in config)
- Allow grouping by multiple columns
- Handling NaN while creating individual groups
- Handling '+' separrated group names

(Adding missing columns)

Requires the file of manual-surveys-to-add to have a consistent country column name and entries.

This is moves field area calculations out of the source_gen package and into the server-specific load function.

Instead of the files unzipped. Requires a corresponding change in EpiModel.

Supporting ongoing collaboration with Mauricio Fernandes and Felipe de Vargas, and Will Thurston, to develop wheat blast and fusarium head blight models driven by UK Met Office met data.

This processor is put it a subdirectory called 'extra' because it is not part of the core products being generated at Cambridge. As such, it will not have substantial documentation or testing, until a time when it is made a core product, or superceded by work elsewhere.

So it is available for other components to import

So it is available for other components to use

adding csvs as well as ncs for RIE files while waiting for EPI pipeline to stop expecting csvs by default

splitting out some csv parsing functions