[FLINK-1174] [streaming] Added window join operator
[streaming] Enhanced BufferTimeout functionality for StreamRecordWriter
Change TypeExtractor to support interfaces within classes

Before, the pojo analyzer would try to analyze a field of type List
or Map and fail. Now we catch the exception and create a GenericTypeInfo
for the enclosing class because the avro serializer can in fact
serialize objects that have fields of interface type.
[scala] Add macroparadise to enable Quasiquotes
[FLINK-1191] Add support for Scala Collections and Special Types

"The special types" are Option and Either. This should work for all
Scala collections except SortedSet and SortedMap, for which the type
checker prints an error message.
[scala] Make getType public in Scala DataSet
[scala] Add union operation to Scala ExecutionEnvironment
[FLINK-1005] By default, new objects are created for each element in group operations
[FLINK-1214] Prevent partitionings on subsets of fields from being pushed down