Merge pull request #50 from william-g-vaughan/master

Add transpose UDF
Rename Transpose to TransposeTupleToBag

Also removed some log spam, added some javadoc.
Add exec and accumulate tests for Sessionize
Make SessionCount also implement Accumulator interface

Also added exec and accumulate test cases.
Don't expose certain classes in javadocs to make them cleaner
Sampling documentation cleanup
Minor doc fixes [ci skip]
Doc change [ci skip]
Doc change [ci skip]
Merge pull request #51 from matthayes/master

Sessionization improvements
Use AccumulatorEvalFunc instead of interface so no need to implement exec
Fix accumulate for ReservoirSample

The simulated accumulate in AlgebraicEvalFunc doesn't work in this case.  Added test cases for exec and accumulate.
Add weightedSampleLimitExecTest
Add sampleByKeyExecTest
Add reservoirSampleAlgebraicTest
Merge MD5 and MD5Base64 into single implementation
Add exec and accumulate tests for StreamingQuantile
Merge pull request #52 from matthayes/master

Add more sampling tests
Add exec and accumulate VAR tests
Validate assumption in VAR initial algebraic method, and add algebraic test cases