add acc_cond::is_hyper_rabin() and acc_cond::is_hyper_streett() functions
Hyper-Rabin is disjunction of Streett (as used by Emerson & Lei), and Hyper-Streett is conjunction of Rabin. These two names were introduced by http://www.faculty.idc.ac.il/udiboker/files/AutomataTypes.pdf