Simplify code using asMatrix()
This is based on dune-common!656 (merged) which introduces Impl::asMatrix()
using this we can avoid many Hybrid::ifElse
constructions which increase complexity of the implementation and error messages.
Furthermore we can drop toMatrix()
which fixed #63 (closed).
This is a clone of !288 (closed). Is was created in order to tell the CI to use the corresponding branch in dune-common using a matching branch name.
Edited by Carsten Gräser