Moved all not yet promisified files to sitegin/legacy

This allows it to run without compiler
(namely VS on Windows).

Image minification won't work when LWIP is
not available. App will warn you about it.

It will also generate lightbox for every image
even those which are under 512.

It also normalizes every path to path/to/file
from path\to\file.

+ Better compileonly exit detection