Code improvements:
  - Standardize MPI communicator use (not always COMM_WORKD);
  - Moving operator requirements to continuous level;
  - Add task parallelism paradigm;
  - GPU: Multi-Scale advection reorganisation on GPU (reuse of remeshing formula);
  - GPU: Reuse buffer across different discretization of the same field.

Add new case in demo MPI. \n Redistribute improvement :\n   - consider ghosts in interComm data transfers; \n   - move MPI subArrays creation to setup;  \n   - improve MPI requests storing. \n Fix use of proper rank from topology.

Fix real precision in SCALES (removing implicit conversions). Fix bug in computing remeshing indices from particle adimentional position (integer translation after floor position).

Fix bug in HDF5/VTK output
Fix bug in field initialization
Modif in FD and diff operators

general updates concerning NS benchmark with bluff bodies (flow past sphere, etc ...) - still some problems to solve ...

Adaptative vorticity projection according a given criterion + velocity correction (to prescribe proper mean flow and ensure the desired inlet flowrate) + some updates in adaptative time step procedure

Documentation related to velocity correction (flow rate prescription at the oulet of the box-domain ...)