Add access to generator-level jets

The code is updated to match the (forthcoming) release 53X.02.05 of the
single-top package. The package can store generator-level jets as
four-momenta only or add a number of status-2 heavy-flavour quarks
nearby, depending on the settings. Currently, PECFwk reads four-momenta
only; although, code blocks to access the numbers of heavy flavours is
included but commented out. The GenJet class contains fields to host
numbers of quarks nearby.
Prevent framework to read generator jets when not requested
Add access to pile-up rho
Update b-tagging scale factors to recommendations for EPS'13

Apart from new numbers, scale factors for the JP algorithm are removed
completely. Add scale factors for two new algorithms: CSVV1 (the scale
factors are official) and CSVSLV1 (experimental). However, the two
algorithms cannot be exploited in the current version of PECFwk.