basics for a matrix that is a mix of dense & sparse data
rowFilter
rowSubset & SubsetMatrix
most members are public vars
very basic demo of boxwood integration
get --> apply, some utils & comments
enum featureset matrix, partial tests
enum matrix is a MixedRowMatrix; expand tests a bit
colsums
oops, missed a file
rowSubset that takes a predicate
slight improvement to test / demo
minor cleanup
fix project def
another constructor; type annotations in test code