Generate correct html links with Lib.Fabricator.md()

[woeps]

Currently links in md files are only parsed by omd and therefore don't produce correct href attributes in resulting html links.

The (re)fabricator(s) for md need to be adapted: probably just replace all links to md files with links to the same relative path but with html extension.

This should be easier after #18 is resolved. Additionally fabrics' names should be the relative file path by convention. When writing a fabric to disc the generated file shall be named according to the fabric's name, but with slashes replaced by underscores.