Added support for manual override of the automatically detected mesh file format

src/TNL/Meshes/DistributedMeshes/loadDistributedMesh.h

src/TNL/Meshes/TypeResolver/TypeResolver.h

src/TNL/Meshes/TypeResolver/TypeResolver_impl.h

src/TNL/Solvers/PDE/TimeDependentPDESolver_impl.h

src/TNL/Solvers/PDE/TimeIndependentPDESolver_impl.h

src/TNL/Solvers/SolverConfig_impl.h

src/TNL/Solvers/SolverInitiator_impl.h

src/Tools/tnl-decompose-mesh.cpp

src/Tools/tnl-grid-to-mesh.cpp

src/Tools/tnl-mesh-converter.cpp

src/Tools/tnl-view.cpp

src/Tools/tnl-view.h