Interpolate to a structured grid

[iuryt]

The unstructured grid is awesome for running for coastal regions, but the analysis of the outputs is extremely difficult. I suggest interpolating the model output to a regular grid. First we can try doing for a rectangle cartesian grid.

We need to find a way to avoid interpolating within the continent. One way is to convert to NaN all grid values beyond a prescribed distance to original nodes. Maybe using the maximum distance between original nodes. We can try and see if it works.