Erik. ComputeGradientByPoints main lls solver from alglib changed to MKL version.
Erik. Temporary commit. Utility kernel functions GetCellValues, IsDummyCell, IsLocalCell implemented
Erik. Boundary conditions rewritten/
Erik. Added ParallelExchangeGradients kernel function but not implemented.
Erik. Face connectivity info rethinked. Accordingly changed everything. Now face store global indexes of neighbour cells.
Erik. Debug information output cleanup. Also TimeStep now precisely reaches MaxTime
Erik. Added data snapshot functionality every few iterations.

Other changes:
1) .gitignore changed to ignore cgns, log and video
2) CGNSWriter now writes iterative data (time, iteration) to solution file
3) SimulationType solver parameter added
Erik. Periodic boundaries implemented. For now without rotations.

1) gengrid2D updated accordingly
2) fixed critical bug in gengrid2D
3) added new class to configuration
4) periodic boundaries tested sequential and parallel
Erik. Added rectangular 3D grid generator with possible periodic boundaries.

Other changes :
1) Fixed bug in grid.h for calculation of cell geometric properties.
2) Fixed bug in kernel.h for calculation of grid geometrics properties.
3) Added test for 3D fully periodic grid.
Erik. ShearLayer test implemented. Major cleanup. gengrid1D rewritten.

1) GenGrid1D rewritten, but not tested.
2) Changes in Roe solver, not tested.
3) Added cmake file and .gitignore changed to ignore CMake temporary files.
4) Major clean up. All unused files removed. Grid class get rid of all obsolete fields.
5) Several bug fixes and refactoring.
Erik. LomonosovFortovGasModel implemented for new equation of state of condensed matter (stainless steel, plumbum).
Erik. CGNSReader bug fixes and new element types support.
Erik. New RiemannSolver base class, HLLC solver implemented for general EOS.

1) Also signum function and new file utilityfunctions.h for storing utility functions
Erik. gengrid1D revised, bug fixes.
Erik. Reference point. Running and tested HLLC solution for Sod shock tube test.

1) Some kernel modifications.
Merge branch 'erik.gradients.calculation'