Upgrade to commons-math 3.2
Poissonized Sampling With Replacement
Change SampleOperator to use sample weight framework
Fix materialization of rows with zero sample weight
Fix warnings in AbstractTestQueries
Add support for rescaled poissonized sampling
Add SQL documentation
Rename analyzer.approximate-queries-enabled

Change name of config flag to analyzer.experimental-syntax-enabled,
since it's used to gate more than just approximate queries (rescaled
sampling)