Physical Actions

[marcusrossel]

On branch physical.

I think we can more or less easily extend the formalization with physical actions.

We will probably need to:

• Add a Component.phy (and rename Component.act to Component.log).
• Add an execution step which handles physical events and can always be taken (figure out the precise semantics for this first though).
• We may also have to add wall clock time to Execution.State.

Can we still show execution to be deterministic if the physical actions occur at the same wall clock times across executions?

cf. Marten's dissertation page 67