Avoid a pyfaust PALM4MSA runtime crash when the constraint/projector list is...

Avoid a pyfaust PALM4MSA runtime crash when the constraint/projector list is not consistent (a constraint to another one or to the matrix to factorize).

- The new function for the verification is pyfaust.factparams.ParamsPalm4MSA.are_constraints_consistent.
- The test is ran in pyfaust.fact.palm4msa directly so that even if the ParamsPalm4MSA structure instance has been modified manually, the error will be detected.
- A comprehensive and precise error message is printed (Exception) to advise users.
- New shape attribute in pyfaust.proj.proj_gen pyfaust.ConstraintGen classes and sub-classes (ease the verification process in ParamsPalm4MSA).