RTC — refactoring of the ExecutionContext model element

The model element ExecutionContext, which is currently an interface, has association ends and a state machine. Therefor, it would be more correct to model it as a Class instead. Its operations can be moved to a new Interface "ExecutionContextOperations" that will be implemented by the Class ExecutionContext."

ExecutionContext should be a Class so that it can have a state machine and association ends. However, a separation between Class and Interface is felt to be a good design. Therefore, the operations of ExecutionContext shall be moved to a new Interface ExecutionContextOperations, and ExecutionContext itself shall become a Class.