MPI implemented for CPU and GPU in 2D but meshFunction.template synchronize< Communicator >(); doesn't copy overlaps.

Lbm

See merge request !26

Some of them are just turned off and need to be fixed properly later.

It is either from subdomain boundary to overlap or vice versa.

Added macro TNL_MPI_PRINT_COND for conditional print outs.

Set-up of the distributed grid subdomains overlaps is taking the actualy applied periodic boundary conditions into account.

There is no overlap if the periodic boundary conditions are applied within one MPI process.

Subdomain overlaps for the periodic boundary conditions is set only when periodic neighbor is not the same MPI process.