changes to allow the new spatial points coming from the MetOffice to work.

It is possible to specify which spatial points file to use in the main config json. The default file will be used if not specified. This will allow us to perfrom historic runs with the old grid and specify manually.
The country-level points filtering used by the postprocessing steps (beofre plotting) now round down the acuracy when filtering points. This allows the country filtering to work with both the new and the old grid, as the differece is lost in the rounding