Swiss-army-knife file compressor/archiver

#1Support for zstd dictionaries

This looks like a great tool, definitely keen to give it a go sometime soon.

I wad wondering if it would be difficult to add support for zstd dictionary creation from a corpus of files, and usage when compressing using zstd. something like sak train -d dict files.. and sak compress foo.csv foo.zst -d dict (obviously the exact interface isn't too important).