TwoVersionScheduler

goes through the whole turn lifecycle

• create a new turn and put it on the stack
• run the lock phase
• the turn knows which reactives will be affected and can do something before anything is really done
  • run the admission phase
• executes the user defined admission code
  • run the propagation phase
• calculate the actual new value of the reactive graph
  • run the commit phase
• do cleanups on the reactives, make values permanent and so on, the turn is still valid during this phase
  • run the observer phase
• run registered observers, the turn is no longer valid but the locks are still held.
  • run the release phase
• this must always run, even in the case that something above fails. it should do cleanup and free any locks to avoid starvation.
  • run the party! phase
• not yet implemented

Name of the scheduler, used for helpful error messages.

Returns a string representation of the object.

The default representation is platform dependent.