Rationale: reserve the behavior folder for trace-based semantics.

These lemmas really constitute an analysis of the basic consequences
arising from the chosen semantics and hence logically belong to the
"analysis" part of Prosa.

This patch adds the classic EDF optimality argument: by swapping
allocations, any schedule in which no job misses a deadline can be
transformed into an EDF schedule in which also no job misses a deadline.