Separate variables over multiple netcdf files

[dalmijn]

Feature type

Adding new functionality

Improvement Description

Begin able to split up the staticmaps over multiple files.
Able to separate the variables in forcing files.

Implementation Description

I would say a simple check on e.g. extent (mainly exact coordinates) and a simple strict merge strategy should suffice.
As far as I understand, NCDatasets support opening mf (multiple files) datasets.

Additional Context

Handy for calibrations, quickly exchanging inputs (also for forcing) etc.