Feature/1d3d coupling manager improvements
Improvements to 1d3d coupling managers. Implements the changes of !2190 (closed) in sensible smaller steps. These changes are improvements that resulted from the 1d3d embedded scheme comparisons included in https://doi.org/10.1016/j.jcp.2020.109370.
The kernel coupling manager (which was not very good) has been replaced with the coupling manager from the paper.