Build static site from documentation

[Orhideous]

It's a much more convenient and extensible way to add information about new printers and the various nuances of printing.

This PR replaces #5.

[Orhideous]

Here is a preview: https://orhideous.github.io/niimprint/hardware/

If all goes well, we'll need to replace the repository URL in the mkdocs.yml

[Orhideous]

@AndBondStyle Please, take a look :)

[AndBondStyle]

Taking a look... Well, I see what's cool about a separate site with docs, however with the python library of this size, is it really necessary? I think right now it's more important to just write more docs in plain markdown than migrate them to mkdocs.

With that in mind, I still appreciate the work you did. Maybe let's merge it into the "docs" branch, take some time to add more info (info about supported printers, more info about the protocol etc.), and when it'll start to look substantial, we merge it into master?