Weighted Mean Functionality

[philipc2]

Add support for weighted means

Face Centered Variables

• Use the Face Area as a weight

Edge Centered Variables

• Use the Edge Magnitude as a weight

[philipc2]

Possible code for a weighted face average:

# (dask * numpy) / (numpy) ? 
(self.data * self.uxgrid.face_areas) / self.uxgrid.face_areas.sum()