[Feature Request] Support for PAQ methods

[hyoretsu]

Trying to look into compression, I found there's ZPAQ, which achieved 4.5% more compression than LZMA on Ultra 1024MB dict size and 273 word size.

There's PAQ8KX, LPAQ, ZPAQ, each of which looks incredible. Currently there are only two programs which are able to work with ZPAQ.

Since I don't know how hard it is, there's the PeaZip program, which already implements LPAQ8, PAQ8O and ZPAQ, so you could do something similar to the features acquired from 7-Zip NSIZ and 7-Zip ZS.

[hyoretsu]

~~It technically isn't from the PAQ family, but phda9 is from the same creator as some PAQ's and it's even better than ZPAQ. (achieving 82% of ZPAQ's ratio, though it may be focused on text files like PPMD)~~ It's focused on text files, and works best for enwik9.

~~For reference, here's a ranking on compression algorithms.~~

But the aforementioned ZPAQ feature would still give a huge advantage to switching over to NanaZip.

[Artoria2e5]

One of the things that makes PeaZip so versatile is that it's not afraid to shell out. Can't quite do that here...