Changint methods for the grid topology - get[Cell,Face]NextTo[Cell,Face].

src/mesh/CMakeLists.txt

src/mesh/tnlGrid.h

src/mesh/tnlGrid1D.h

src/mesh/tnlGrid1D_impl.h

src/mesh/tnlGrid2D.h

src/mesh/tnlGrid2D_impl.h

src/mesh/tnlGrid3D.h

src/mesh/tnlGrid3D_impl.h

src/operators/diffusion/tnlLinearDiffusion_impl.h

src/operators/tnlAnalyticNeumannBoundaryConditions_impl.h

src/operators/tnlNeumannBoundaryConditions_impl.h

tests/unit-tests/mesh/tnlGrid1DTester.h

tests/unit-tests/mesh/tnlGrid2DTester.h

tests/unit-tests/mesh/tnlGrid3DTester.h

tests/unit-tests/mesh/tnlGridTester.h