Port instantiations

Add instantiations of aRTA for
(1) fully preemptive,
(2) fully non-preemptive,
(3) limited preemptions,
(4) and floating non-preemptive regions EDF models

Add instantiations of aRTA for
(1) fully preemptive,
(2) fully non-preemptive,
(3) limited preemptions,
(4) and floating non-preemptive regions FP models

File preemption.util is renamed and moved to
util.nondecreasing. The new util file can be used
in both the old Prosa and the new Prosa.