improve terminology about priority inversion
Definition of [max_length_of_priority_inversion] is renamed into [max_lp_nonpreemptive_segment].
Name [max_length_of_priority_inversion] does not make sense, since the following expression is simply a bound on a non-preemptive segment.
\max_(j_lp <- arrivals_before arr_seq t | (~~ hep_job j_lp j) && (job_cost j_lp > 0))
(job_max_nonpreemptive_segment j_lp - ε).