Use ISA-L as a backend for decompression and the lowest compression levels

Have you tried https://github.com/intel/isa-l? It can be installed through conda and then you get `igzip`. It is awesome. - Fastest decompression. (2x zlib) - Very fast level 0 (extra level they added), 1, 2 and 3. Level 1 is 5(!!!) times faster than zlib while compressing better. ISA-L has library functions that can be called. Since crabz is already dynamically choosing zlib-ng over zlib adding ISA-L should be a possibility. The best mix in my opinion is: - decompression: ISA-L - compression level 1 and 2: ISA-L - compression 3 and higher: zlib-ng or libdeflate (depending on format). Thanks for the crabz project and have a nice day!