[BCRSPattern][Bugfix] Fix detection code for empty rows
[PowerGridFunctionSpace] Add a constructor that takes a variadic list of shared_ptrs to children

Such a constructor greatly simplifies on-the-fly construction of nested
spaces by allowing users to simply allocate children via std::make_shared().
[CompositeGridFunctionSpace] Add constructors that take a variadic list of shared_ptrs to children

These constructors greatly simplify on-the-fly construction of nested
spaces by allowing users to simply allocate children via std::make_shared().
[bugfix,pkg-config] Add library to pkg-config file.

Obviously this module ships a library but lacks it in the linker flags
for pkg-config. Therefore the build of modules that depend on an
installed version of pdelab fail miserably with unresolved symbols
when the library is checked for.

This patch solves this by adding the -ldunepdelab to the linker flags.
It should be applied to the release, of course. Otherwise testing _will_
fail.
[LeafLocalOrdering] Make sure to reset fixed size flags if ordering is not fixed size
[LeafGridViewOrdering] Update per-codim fixed size flags at end of update()
[Release] Update version information for PDELab 2.0.0-rc1
[Documentation] Fix typo
[Bugfix][Buildsystem] Update liste of installed headers in backend/

There were both leftovers of removed headers and missing new headers.

This patch fixes FS#1472.

Thanks to Markus Blatt for reporting this.
[GridFunctionSpace] Don't make the stored GridView const

We might want to update the underlying GridView if we want the
GridFunctionSpace to survive operations like adaptivity and / or load
balancing.
[GridFunctionSpace] Store constraints engine as shared_ptr and allow passing a shared_ptr to the constructor

For some weird reason, when the GridFunctionSpace was modified to store
the FiniteElementMap as a shared_ptr and potentially assume ownership of
it, the constraints engine did not receive the same treatment. Usually,
this is not a problem, because most current constraints engine do not
carry any state, so the underlying variable can point at garbage without
any harm, but that is of course not a solution.

This patch changes the GridFunctionSpace to

- use a shared_ptr for storing the constraints engine
- add new constructors that allow passing in a shared_ptr to a
  constraints engine
- export the new shared_ptr via a new method constraintsStorage()
- get rid of the weird defaultce member - if we don't get a constraints
  object, we can just allocate one and store it in our internal shared_ptr
Merge branch 'releases/2.0'

Pull in fixes from 2.0 release branch.

* releases/2.0:
  [GridFunctionSpace] Store constraints engine as shared_ptr and allow passing a shared_ptr to the constructor
  [GridFunctionSpace] Don't make the stored GridView const
  [Bugfix][Buildsystem] Update liste of installed headers in backend/
  [Documentation] Fix typo
  [Release] Update version information for PDELab 2.0.0-rc1
  [LeafGridViewOrdering] Update per-codim fixed size flags at end of update()
  [LeafLocalOrdering] Make sure to reset fixed size flags if ordering is not fixed size
  [bugfix,pkg-config] Add library to pkg-config file.
  [CompositeGridFunctionSpace] Add constructors that take a variadic list of shared_ptrs to children
  [PowerGridFunctionSpace] Add a constructor that takes a variadic list of shared_ptrs to children
  [BCRSPattern][Bugfix] Fix detection code for empty rows

Conflicts:
	dune.module
	dune/pdelab/gridfunctionspace/compositegridfunctionspace.hh