Add library Dune::SPGrid

See merge request !32

[cmake] Incrase minimal required version to 3.16

See merge request !31

[cleanup] Explicitly state type aliases since std::iterator is deprecated in C++17

See merge request !29

Use boolean | as binary operator between bools

See merge request !28

into FieldMatrix.

dune_python_configure_bindings.

Replace deprecated CollectiveCommunication by Communication

See merge request !26

Add jacobian()... to SPGrid's geometry implementations

See merge request !27

This avoids the deprecation warning of the default implementation.
The new methods return transposed views storing references
to the (cached) results of `jacobianTransposed()` and
`jacobianInverseTransposed()`.

DUNE_DEPRECATED replaced with [[deprecated]]

See merge request !23

python overhaul

See merge request !22