Optimal Partitioning for LSH Ensemble

This release adds optimal partitioning for LSH Ensemble. Now, instead of BootstrapLshEnsemble, you can specify whether to use optimal partitioning, BootstrapLshEnsembleOptimal, use the equi-depth partitioning,
BootstrapLshEnsembleEquiDepth as described in the original paper.

First stable release

v1.0.0

update signature serialization interface