Adding CLASSFuel and CLASSFuelPlan,

The first aim to regroup PhysicModels and EvolutionData in the same mother class, 
the second will be used to change the fuel inside the reactor at a set time… note that you can change from fixed fuel to recycled and vice versa :)

those commit compile but does not have been tested on a scenario…

The other commit is to adapt CLASS to the fuelPlan possibilities…
BaM

git-svn-id: svn+ssh://svn.in2p3.fr/class@363 0e7d625b-0364-4367-a6be-d5be4a48d228