Introduction of Communicators and DistributedMesh.

src/TNL/CMakeLists.txt

src/TNL/Communicators/CMakeLists.txt

src/TNL/Communicators/MpiCommunicator.h

src/TNL/Communicators/NoDistrCommunicator.h

src/TNL/Functions/MeshFunction.h

src/TNL/Functions/MeshFunction_impl.h

src/TNL/Meshes/CMakeLists.txt

src/TNL/Meshes/DistributedMeshes/CMakeLists.txt

src/TNL/Meshes/DistributedMeshes/DistributedGridIO.h

...NL/Meshes/DistributedMeshes/DistributedGridSynchronizer.h

src/TNL/Meshes/DistributedMeshes/DistributedGrid_1D.h

src/TNL/Meshes/DistributedMeshes/DistributedGrid_2D.h

src/TNL/Meshes/DistributedMeshes/DistributedGrid_3D.h

src/TNL/Meshes/DistributedMeshes/DistributedMesh.h

...NL/Meshes/DistributedMeshes/DistributedMeshSynchronizer.h

src/TNL/Meshes/GridDetails/Grid1D.h

src/TNL/Meshes/GridDetails/Grid1D_impl.h

src/TNL/Meshes/GridDetails/Grid2D.h

src/TNL/Meshes/GridDetails/Grid2D_impl.h

src/TNL/Meshes/GridDetails/Grid3D.h