Multicore support (parallel decompression)

[stopiccot]

Right now InnoExtract seems to be a classic single threaded program that could be speeded up a lot by using multiple cores.

[dscharrer]

Right. Some installers only use a single compressions stream so there isn't much room for speed improvement (besides decoupling input, decompression and output - might still be worth it!), but many use a new compression stream for each file.

[KiralyCraft]

Looking forward to this! It's amazing even as-is, I am drooling over the idea of implementing multi-threaded support