Introduced Computable which will handle the arguments mapping
between contruction and compute call
Changed the design to simplify the programation:
there is a dictionary in every map2D holding the parameters
we use the introspection to get the arg list of _compute()
and we extract this values from the Map2D dictionary

The Map2D attributes time and dt have also been moved to the dictionary

The FuncMap2D can take any function for computing

The FuncWithoutKeywords can link compute with a function take a list of values as parameter
Every time we add children, global param and at the construction params are to be send to this list
Consequently one should use the ignoreComputeArgs method to remove the params of the list
(Think to remove dt)