HySoP tasks improvements (and fixes)

Dealing with multiple tasks need review (improvements needed in automatic inter-comm setup, and few bugs)

• Bug: incorrect overlapping local and mpi comm for ghosts exchanges (solved in d96857fc)
• Bug: Transposition state must be handled by RedistributesInter (solved in dccb0373 : Transposition states now includes task_id information)
• Bug: Inconsistent field name across tasks (topology id may differ) (solved dfea54d3: used defined var_names is overriding dataset naming)
• Improvement: all-to-all tasks automatic communication (done in 9e06cef1)
• Improvement: atomatic communication between tasks is not handled automatically for parameters (done in 431ba7a5).