filling particles from MHD level

[nicolasaunai]

preliminary thoughts...

let's say the messenger needs to fill particles how does it know it has to take from MHD N,V,P ? how does it even know MHD ? If we have fromFinerInfo and fromCoarserInfo, we can let the MHDHybridMessengerStrategy pick the quantity names required for the schedules. for instance the MHDHybridMessengerStrat knows, because that's its role, that particles need n,V,P (+ particle drawing operation) MHD quantities. It also knows that finerInfo is Hybrid and coarserInfo is MHD. So it is able to take particle names from hybrid, and n,V,P from MHD then it can settle schedules for n,V,P MHD to n_tmp, V_tmp, P_tmp, which are internal quantities to the MHDHybridMessengerStrategy On calling fillIonGhostParticles, this schedule is applied and finer level internal quantities n_tmp, V_tmp and P_tmp are now filled. A RefineStrategy with PostProcessRefine can, from these internal data, draw particles and put them in the appropriate hybrid particle buffer.