Major changes to resolve the problems with missed windows in time based windowing. Introduces so called active policies to resolve the issue
Extended test cases for time policy to verify active policy behaviour and codecleanup in the invocable
Adjusted examples and DataStream. Added new example for the time based windowing.
Introduces an wrapper which makes it easy to use eviction policies in both ways. (reacting on fake elements and ignoring fake elements). While the default is ignoring the wrapper makes it aware.