Implemented generic aggregators for iterations in the API and configuration.
Added PactBoolean type.
Fixed aggregator registration for iteration tasks.
Reworked examples.
Implemented custom aggregators (runtime misses iteration head task)
Finished customizable aggregator implementation.
Added DanglingPageRank example.
Reworked iterative tests.
Reduced logging verbosity for iterations (temporarily commented out monitoring facility for time tracing)
Fixed Union Plan Enumeration.
Fixed Branching Plan tests.