Implement zgrep

[Keruspe]

This would be cool to get us closer to being a drop-in replacement for gnu gzip

[dnbaker]

According to this issue, decompression is fundamentally single-threaded and can't be improved using pigz except for handing other portions of the task to other threads, which can sometimes make a small, but not enormous, difference.

You're better using pigz -dc $file | grep <args>, or , if you're streaming, cmd1 | pigz -d | grep <args>.

I am, of course, no contributor or developer of zlib, so I can't speak for @madler, but I wouldn't keep hopes up.