Add SequenceFile/WritableSequence tests
Added the Sum optimization
More specific type for collecting addends
Choosing different join algorithms in Products based on SizeHints
Removed the additional special case for Sum
Added a simple difference/negation optimization
Added reducers option to the new join functions
Not working propagate
Column propagation seems to work
Changed Longs to BigInt
Added a note for Monoid/Ring confusion in propagate
Fixed a bug in size estimation of diagonal matrices and wrote a test for it
Added a comment for the last case in optimize
Removed sumColVectors from propagate and changed Ring to Monoid
Added a simple row L2 normalization
Removed the unchecked warnings from Matrix2OptimizationTest
Added the zero filter to propagate
Added TODOs
filtering out zeroes in binarizeAs
Changed all toTypedPipe to lazy val to be sure