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