Faiss 1.5.1

Changelog:

• a MatrixStats object, which reports useful statistics about a dataset;
• an option to round coordinates during k-means optimization;
• an alternative option for search in HNSW;
• moved stats() and imbalance_factor() from IndexIVF to InvertedLists object;
• range search is now available for IVFScalarQuantizer;
• support for direct uint_8 codec in ScalarQuantizer;
• renamed IndexProxy to IndexReplicas (now ;
• better support for PQ code assignment with external index;
• support for IMI2x16 (4B virtual centroids!);
• support for k = 2048 search on GPU (instead of 1024);
• most CUDA mem alloc failures now throw exceptions instead of terminating on an assertion;
• support for renaming an ondisk invertedlists;
• interrupt computations with interrupt signal (ctrl-C) in python;
• simplified build system (with --with-cuda/--with-cuda-arch options);
• updated example Dockerfile;
• conda packages now depend on the cudatoolkit packages, which fixes some interferences with pytorch. Consequentially, faiss-gpu should now be installed by conda install -c pytorch faiss-gpu cudatoolkit=10.0.