implementing toy calculation with several observables at a time

• The code from Teddy has been ported here locally.
• A new executable, getToyCalculation has been added, which works in a similar way as the unfolding executables and follows the same convention.
• The daughter classes of Observables have been extended; an analog to Fillers is added, namely Transformer, to provide the necessary operations to the toy calculations.
• A couple of practical changes have been applied:
  • The H_\mathrm{T} range for the cross section ratios has had to be reduced (suspecting float to have too limited precision).
  • #103 (closed) has been addressed.
  • The binning for the dijet mass has been simplified (no difference between central and forward regions).