Minor documentation updates

* moving the documentation to readthedocs.org
* adding GitHub URI to the source
Minor documentation update

Some directives where not reconised by the standard restructured text
parser from docutils.
Bug: comments are not always correctly handled

This commit fixes:

* comment identifiers are evaluated inside quotes (but comment quoting
  does work)
* comment does not stop the evaluation of the line, especially when
  quoted fragments are identified after the start of the comment
* some ugly space characters before the new-line

New tests has been added.