Make aggregations combinable and remove AVG aggregation
Fix hash partitioning for new java api
Fixed RecordOutputEmitter and extended OutputEmitterTest for hash corner cases
fixes toString return value of min aggregation
Merge pull request #874 from vasia/fix_min_aggr_tostring

Fixes toString return value of MinAggregationFunction
Improved error handling when fetching optimized plan of programs.
Improve ConnectedComponentsExample with constantfields annotation
Aggregate Operator sets its semantic properties.
added murmurHash implementation
Minor cleanups for hash partitioner
Fixes an issue when generating a type erasure exception in TypeExtractor.