check-point on implementing maxtrix-optimized proximity forest. We have
an initial implementation of the ProximityTreeMatrix class, but with
some issues on maintaining the labels with the shuffled samples?
refactored implementation of ProximityTreeMatrix to fix a bug, but also
to reduce the amount of unique code from the base class and make the
interface much more similar.
ProximityForestMatrix works, using a serial build process, but it is
still reasonably fast. A forest of 8 trees takes about 20 seconds to
index 100K vectors of 100-dimensions.