* CompressionParameters now has a estimated_compression_context_size() method.
zstd.estimate_compression_context_size() is now deprecated and slated for
removal.
* Implemented a lot of fuzzing tests.
* CompressionParameters instances now perform extra validation by calling
ZSTD_checkCParams() at construction time.
* multi_compress_to_buffer() API for compressing multiple inputs as a
single operation, as efficiently as possible.
* ZSTD_CStream instances are now used across multiple operations on
ZstdCompressor instances, resulting in much better performance for
APIs that do streaming.
* ZSTD_DStream instances are now used across multiple operations on
ZstdDecompressor instances, resulting in much better performance for
APIs that do streaming.
* train_dictionary() now releases the GIL.
* Support for training dictionaries using the COVER algorithm.
* multi_decompress_to_buffer() API for decompressing multiple frames as a
single operation, as efficiently as possible.
* Support for multi-threaded compression.
* Disable deprecation warnings when compiling CFFI module.
* Fixed memory leak in train_dictionary().
* Removed DictParameters type.
* train_dictionary() now accepts keyword arguments instead of a
DictParameters instance to control dictionary generation.