Replaced old `Topology` template parameter based on template recursion
with a `GeometryType::Id` parameter.

avoid signed/unsigned warning

(Singleton)TopologyFactory to stay in dune-geometry

The new implementation class is called
Nedelec1stKindSimplexLocalFiniteElement.  Simplex dimension and
finite element order are template parameters, but this is an
investment into the future:  Only the case dim==2, order==1 are
currently implemented.

Added `RT03LocalFiniteElement` a `RaviartThomas` local finite element for simplices with `dim=3`
and `k=0`.

Used the basis returned from `RaviartThomasSimplexLocalFiniteElement()` (see `dune/localfunctions/raviartthomas/raviartthomassimplex.hh`).

Passed all tests from `dune-localfunctions`.

By deprecating the generation of the old-to-new-interface
wrapper we issue a warning whenever an old style function
is used. To avoid warnings in checks of the deprecated
interface the deprecation is disabled by defining the
flag `DUNE_DEPRECATED_INTERPOLATE_CHECK=1` for
`dune/localfunctions/test`.

Lisa Julia Nebel authored Apr 02, 2020 and Oliver Sander committed Apr 03, 2020

One of the shape functions of the second-order Lagrange element for
pyramids was implemented wrongly, and the derivative along with it.
This went unnoticed for a long time, until I saw that the element
was not able to represent constant functions.

This class BrezziDouglasMariniSimplexLocalFiniteElement has the domain
dimension and the polynomial order as template parameters, rather
than encoding them into the class name itself.

This class implements Lagrange finite elements on simplices
with compile-time dimension and order. It currently does not
cover more general dimension/order situations than what is
already available in dune-localfunctions, but it gathers the
plethora of different Pk3DNodal, PkNodal, P1Nodal, etc implementations
under one single name.

The implementation is generic, and the patch adds a unit test
that tests all dimensions <= 4.

That way it becomes The One Header To Include(TM) for all
Lagrange Finite elements.

It includes all headers from the `hierarchical` directory.

This is a breaking interface change. Hence we should
document the removal and what to use instead of `clone()`.

If you want a list item withz multiple paragraphs in markdown,
then (at least the first line) of any paragraph following the
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those paragraphs will not be part of the list item, cf.
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BTW: Don't ask we what to do for second level items with
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