Optimize the size of the hydro data box read for each domain. Reduces a little the computational time of weight calculation.

Some clean-up of the code and supression of the call to the plot routines in the main. That is replced by Anthony's code.

I verified that we can read the weight with another processor partition as the one use to compute them.
Small differences appear because of different rounding errors on the individual processors and the core proc who gives his values to the file.

Generalized the code so it could be executed from anywhere.
Created a new test infrastruture.

But still, it does not fully solve the issue with SphericalGeometry