Apply variable naming convention to Richards local operator
The following discussions from !93 (merged) should be addressed:
Before removing the WIP again, I will modify the name convention within the local operator. In !112 finally I got to a name convention that I think is more expressive:
<description>with respect to the inside entity.
<description>with respect to the outside entity.
<description>with respect to the face entity (or intersection).
<description>with respect to the global grid.
<description>in normal direction.
Notice that when working with gradients, the suffix for normal direction can be combined with the first three suffixes (
_n_f). When it's not specified, is understood that it is with respect to the face (
Adjust the local operator of the Richards model to this naming convention.
How to test the implementation?
Everything works as before