[wilson_fits] restructure framework

o group constraints in constraints.py
o detect nuisance parameters from constraints in get_nuisance(constraints)
  in nuisance.py
[wilson_fits] rename scenarios, correct option "form-factors"

o use more local initial mc_proposal
o load constraints using constraints.py
o for scalar: set "W0" in vb
[Thesis.odt] todos for chapter VBGauss

o add citation [DLR77] (considered as original EM-algorithm)
o add reminder to cite Bishop's book