To be used in StressBC which gets improved results for q<0.5. q=0.5 still set as default argument for all other BCs

Added SG model to StressBC, added Timer-class which wraps existing timer in Simulation, added round-off correction in TurbulentViscosityCumulantK17CompChim_Device (testing ongoing)

Fixed periodicity issue by addind STOPPER_OUT_OF_GRID_PERIODIC flag. Further preparaions for stress BC

and refactore this function for better readability

and refactoring this function for better readability

Remove them from LevelGridBuilder

For communication after interpolation fine to coarse