Refactoring the Dirichlet and the Neumann boundary conditions.

simple-solver and make-project were removed from examples.

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

Fixing the solvers.

Changing explicit solvers - Merson and Euler.

There is gap of missing commits.

Adding edge-skip to grid comparison function.