added WallModelProbe, replaced PostProcessingVariable with Statistic in Probe (and all derived classes) and added some documentation

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

Added configBoundaryLayer.txt. Added Slip BC allocations to GridGenerator. Can now be used again, but thus far ignores normals and uses the default q's set by the SideType. Modified NoSlip BC, now just adds a velocity BC with zero velocity.

adds wrapper for gpu WIP

(cherry picked from commit b3cf5c2eb5dad849b6c8d71552ca995fbe7a487e)

(cherry picked from commit 07a4f9636751c016f7e73ff58b988da59f735921)

(cherry picked from commit eb6aadaaa24eff6acdd8563f1b5fef1b3ed21e2a)

cherry-pick 56b49f3

(cherry picked from commit 1c1c12968df801d995d39e0aaa4d2950eee7a73a)

(cherry picked from commit 4d49e04593989485e1c3710fe497fb45ae41d588)