Add Cell function for packaging games with the engine for distribution

[Eggbertx]

This would be really helpful for easily distributing the game and necessary libraries and optionally packaging them in a .zip archive for people who might not have miniSphere installed.

[fatcerberus]

This was an idea I had a while back, to be able to say cell pack on the command line and have it zip up a self-contained bundle. I ended up not actually implementing it at the time because I wanted to figure out how to make it adaptable to Oozaru too. Now's probably as good a time as any to revisit.

[Eggbertx]

I didn't think about this when I created the issue, but I think it would also be really nice if there was an option to have Cell download the latest release from GitHub for Windows, Linux, and macOS, so you could easily distribute your game for the three platforms without limiting yourself to your own.