New Debuging Tool - StackBackTrace with File and Line info - copied from web, possible memory leaks.
Heavy unsystematicly bastled into TNL but usefull.

(Jak má člověk propalovat čas v Ostravě, když mu to školitel rozbil....
git log -L60,60:src/TNL/Meshes/GridDetails/Traverser_Grid3D_impl.h)

* mpi:
  Fix DistributedIOTest

* cineca/ci:
  Added configurations to build with MPI on the CI
  Disabled building Benchmarks, Examples, Tools and Python in one half of the CI jobs
  Reorganization - removed useless subdirectory
  Reorganization - moved examples into src
  Reorganization of benchmarks - moved into src

The benchmarks, examples, tools or Python bindings are not run by the CI, so
we just check that they can be compiled. But we don't have to do it twice...

- There is an RAII wrapper called ScopedInitializer to handle
  finalization due to C++ exceptions and to avoid calls to Finalize in
  all exit branches.
- Fixed signature of MpiCommunicator::Init to match that of MPI_Init.

Even the methods for specializations without storage have to return
something, which was not the case...

The original was simpler/more readable and we require GCC 5.0 now.

This reverts commit d920a278.

The std::isnan method can be safely used in host code (if the compiler
is not moron). There is no device code which uses isnan so the
TNL::isNan function is useless.

This reverts commit 0eff2f63.

This shuts up a lot of GCC warnings...