Refactoring with the shared pointers.

src/core/tnlSharedPointer.h

src/functions/tnlMeshFunction.h

src/functions/tnlMeshFunction_impl.h

src/functions/tnlOperatorFunction.h

src/operators/geometric/tnlCoFVMGradientNorm.h

src/operators/tnlOperatorComposition.h

src/problems/tnlHeatEquationProblem.h

src/problems/tnlHeatEquationProblem_impl.h

src/problems/tnlPDEProblem.h

src/problems/tnlPDEProblem_impl.h

src/solvers/linear/krylov/tnlBICGStabSolver.h

src/solvers/linear/krylov/tnlBICGStabSolver_impl.h

src/solvers/linear/krylov/tnlCGSolver.h

src/solvers/linear/krylov/tnlCGSolver_impl.h

src/solvers/linear/krylov/tnlGMRESSolver.h

src/solvers/linear/krylov/tnlGMRESSolver_impl.h

src/solvers/linear/krylov/tnlTFQMRSolver.h

src/solvers/linear/krylov/tnlTFQMRSolver_impl.h

src/solvers/linear/stationary/tnlSORSolver.h

src/solvers/linear/stationary/tnlSORSolver_impl.h