This doesn't change the behavior of segment_image().  I just refactored it to
avoid duplicate code and generally cleaned things up a little.
Added database::last_insert_rowid()
Added missing #include
Added initial version of find_candidate_object_locations()
Added a set of new LSH based hashing functions meant for use
with larger vectors and high bit sizes than the current LSH tool.
These are the new hash_similar_angles_xxx objects.
Added find_k_nearest_neighbors_lsh() and hash_samples()
removed cruft
A minor change to avoid a compiler warning from clang
Added unit tests for the find_k_nearest_neighbors_lsh() method
and related tools.
fixed typo in spec
updated docs
Made graph_utils_threaded.h #include graph_utils.h
updated docs
Added code to avoid a potential division by zero
Added a numerical constants file numeric_constants.h.  Expanded the
running_stats object in statistics.h by including two functions that
compute the unbiased empirical skewness and kurtosis of a set
of real numbers.  Added unit tests for these functions in statistics.cpp.
Removed the max_n feature from the running_stats object since it's actually
been broken for a while and I doubt anyone ever used it (this also simplifies
it's interface).  Note that this change, along with the previous change by
Steven breaks backwards compatibility with the previous serialization format
for running_stats object.
updated docs
fixed typo in docs
Made algs.h include numeric_constants.h since it adds essentially no overhead
to the compilation process but makes these convenient constants always
available.
Removed unneeded #include