In anticipation of future reorganization efforts by Sophie, there's no
point in keeping the two kinds of definitions separate.

Move everything into the new namespace starting with 'prosa' rather
than the bland 'rt'.

The main restructuring thrust is nearing completion, so let's get rid
of the `restructuring` namespace.

This is not yet the final organization, but already an improvement.

Move main high-level results to separate top-level `results` module.
Rationale: Let's make it very clear where to find the main, high-level
results in Prosa, and at the same time let's declutter the analysis
namespace.

Other notable change, apart from moving files around:

- move two key analysis definitions to analysis.definitions
- split RBF definition and facts into separate files
- move facts about ideal schedule to ideal_schedule.v

The Prosa notion of priority-driven scheduling depends on the
preemption model. That is ok; any theory that doesn't want to deal
with non-preemptive sections can simply Require Export the fully
preemptive model and be done with it.

With this patch, the model module is finally completely independent of
any definitions or proofs in the analysis module.

This fixes all warnings about ambiguous module names and resolves #49.

It also highlights that we still need to cut down on superfluous
Require Import commands in recently ported files.