cleaning up and new flexibilities in MDFit

This is work in progress. Already done:

• a huge cleaning up
• deal with warning due to ClassDef
• add RooHILLdini and RooHORNdini (functions created by Paolo Gandini and Donal Hill)
• change logic in MDFit:
  • delete special fucntions for signal and combo (no needed anymore)
  • able to use analytical function for all components (work in progress, code there, only B2DK bkg contribution is changed)
  • unify code for all components
  • code should be backward compatible
  • split basic function into separate files:
    • create new namespace BasicMDFitPdf:
    • all basic function from Bs2Dsh2011TDAnaModels are moved there
    • the namespaces changed in the fitShapes and runMDFitter_Bd
    • waiting for approval from Vincenzo for moving other functions from Bd2DhModels
    • build interface BasicMDFitPdf::buildAnalyticalShape which allows to pick up correct shape
• move tryPdf, checkPDF, checkVar to GeneralUtils
• change code for all background models
• move DsK/DsPi models to Bs2DshModels.{h,cxx}
• change all config files
• delete uncessary functions after full migration
• add buildGlobalPdfMDFit(...) function which build the generic background model as sum (pdf_i * yield_i), where i is the number of independent backgrounds. Function can be used for the DK/DPi/DsstPi models.
• to-do:
  • new functionality can easily allow to fit whatever dimensions you want (order and number), very flexible!