Bugfix, set Neumann boundary conditions for the subgrid TKE at vertical walls instead of implicit Dirichlet conditions that always act as a sink term for the subgrid TKE. Therefore, add new data structure for vertical surfaces and revise the setting of the boundary grid point index space. Moreover, slightly revise setting of boundary conditions at upward- and downward facing surfaces. Finally, setting of boundary conditions for subgrid TKE and dissipation (in RANS mode) is now modularized. Update test case results.
