Implementing operator function test.

Removing parameter mesh from method getValue in operators.

Refactoring the Dirichlet and the Neumann boundary conditions.

Min. interations feature was fixed in the GMRES method.
Timers for explicit and semi-implicit timestepping were added.

Adding OpenMP support.

Adding new classes - AnalyticSolution, NeumannBoundaryCondition, DirichletBoundaryCondition, LinearDiffusion, RightHandSide, TimeFunction, ZeroRightHandSide
Updating classes (implementation of partial derivations) - SinWaveFunction, ExpBumpFunction, SinBumpsFunction
Updating classes (modifying and adding new methods) - SimpleProblemSetter, SimpleProblemSolver
Modifying - simple-solver.cfg.desc