SLB: added several new Hlt2/sprucing lines and builders
Created new basic builders for tauons and fake muons in base_builder.py. Created a generic charm-hadron builder and several specific instantiations of it in charm_hadron_builder.py. Added new beauty-hadron builders for semitauonic lines and for b->u lines. Added several lines for semitauonic decays and for b->u transitions. Extended the framework to run SLB lines in either Hlt2 or sprucing mode, and created the sprucing version of two semitauonic lines.