Moved keys for inputs/outputs of workflow tasks from AbstractTaskImplementation to AbstractWorkflowNodeImplementation, in order for ScenarioNodes to use them. Also merged KEY_SDF_SCENARIO and KEY_PI_SCENARIO into KEY_SCENARIO, since we merged PreesmScenario and PiScenario into PreesmScenario.
Added a key for input/output MemoryExclusionGraphs and Sets of MemoryExclusionGraphs.