[FEATURE] Autogenerate prefix for absolute links

Add a helping variable to build absolute links to
the root of the domain without handling the URL scheme.

This way all links could get rid of the host & domain part,
and just build absolute links to the root instead.
(Replace "[https://example.com/foo/] + [functions.js]" with
"[/foo/] + [functions.js]")

Refs #79