Modernize PrAlgorithms

• prefer auto
• remove use of BOOST_FOREACH
• prefer range-based for loops
• prefer implicit destructors
• prefer direct member initialization
• prefer emplace_back over push_back
• prefer inheriting from extends over virtual inheritance
• add final
• remove inclusion of unused header Event/TrackFunctor.h
• prefer assignement over hard-wired set of push_backs