Add Param.py for precision and order global parameters. Cleaning.

parmepy/new_ParMePy/Domain/Box.py

parmepy/new_ParMePy/Domain/CartesianGrid.py

parmepy/new_ParMePy/Domain/ContinuousDomain.py

parmepy/new_ParMePy/Domain/DiscreteDomain.py

parmepy/new_ParMePy/Domain/ParticleField.py

parmepy/new_ParMePy/Operator/Advection.py

parmepy/new_ParMePy/Operator/AdvectionDOp.py

parmepy/new_ParMePy/Operator/ContinuousOperator.py

parmepy/new_ParMePy/Operator/DiscreteOperator.py

parmepy/new_ParMePy/Operator/InterpolationDOp.py

parmepy/new_ParMePy/Operator/RemeshingDOp.py

parmepy/new_ParMePy/Param.py

parmepy/new_ParMePy/Problem/ContinuousProblem.py

parmepy/new_ParMePy/Problem/ContinuousTransportProblem.py

parmepy/new_ParMePy/Problem/DiscreteProblem.py

parmepy/new_ParMePy/Problem/DiscreteTransportProblem.py

parmepy/new_ParMePy/Utils/GPUParticularSolver.py

parmepy/new_ParMePy/Utils/Linear.py

parmepy/new_ParMePy/Utils/M6Prime.py

parmepy/new_ParMePy/Utils/ODESolver.py