This is probably not what the author intended. MeshFunctionEvaluator
should not be used directly, mesh functions should be evaluated only by
MeshFunction::operator= -- but it can't cache the evaluator instance
because it is a template method.

Generalized grid traversers and PDE solvers classes for vector functions, added OperatorAdapter and generalized operators for multiple components

This is a generalization of mesh functions for vector fields, which
represent multiple values at each mesh entity. This will be useful for
solving systems of PDEs. The default value of the MeshFunctionDimension
parameter is 1 to preserve original behaviour.

* origin/mesh: (251 commits)
  Updated CMakeLists.txt files for meshes
  Added missing __cuda_callable__ flag to MeshEntity
  Fixed comparison between signed and unsigned
  Optimizing mesh initializer, replaced EntitySeedKey with EntitySeedHash
  Added timer to MeshReaderTest
  Fixed SubentityAccessLayer
  Fixed typo in mesh StorageLayer
  Removed checkCells method from the mesh initializer
  Switched static functions to inline
  Fixed comparison between signed and unsigned
  Fixed constness of reader in MeshTypeResolver
  Renamed VTKEntityType to EntityShape
  Renamed MeshConfigBase to DefaultConfig
  Removed static asserts from MeshConfigBase
  Fixed internal linkage of functions in VTKEntityType.h
  Added specialization of getEntityMeasure for quadrilaterals
  Simplified and generalized the getEntityCenter function
  Added getEntityCenter and getEntityMeasure functions
  Removed unused methods
  Removed GlobalIndexType and LocalIndexType from the public interface of MeshEntityTraits
  ...

* master:
  Documentation.

Python bindings

See merge request mmg/tnl-dev!2

And of course our implementation is faster ;-)

It cannot work because indices are not initialized to -1 anymore. The
checks in the MeshBuilder class should be enough.

This way GCC does not complain that they are not used in some
compilation units.