Concrete arrival sequence

Added definitions and facts about the concrete arrival sequence, used in Poet to generate assumption-less certificates

implementation/definitions/maximal_arrival_sequence.v

-Require Import prosa.model.processor.ideal.
-Require Import prosa.model.task.concept.
-Require Import prosa.model.task.arrival.curves.
-Require Export prosa.analysis.facts.model.task_arrivals.
-Require Export prosa.util.all.
+Require Export prosa.model.task.arrival.curves.
+Require Export prosa.util.supremum.
 
 (** * A Maximal Arrival Sequence *)