relax SVN archive

Fix for bug #20189 (https://gna.org/bugs/?20189).

The Sequence GUI element can no handle values of None.

Created the User_functions.test_value_set GUI test demonstrating the failure of the value.set user function.

Added a subsubsection label to the data model chapter of the user manual.

Spacing fix.

Removed the \pycodestar{} references in the development chapter.

This command has been deleted as \newcommand cannot have \verb inside it! The \pycodestar{x}
references have been changed to \verb*!x!.

Removed \verb from the \newcommand definitions as that is forbidden in LaTeX.

Now Python code is formatted using a small TT font.

Added a section label to the intro chapter of the user manual.

Modified the dauvergne_protocol sample script to handle tryptophan indole NE1 data.

The citations chapter is now included in the HTML version of the user manual.

For some reason, a file named 'cite.tex' cannot be handled by latex2html.

The latex2html compilation of the user manual now ignores the \bibitem{} commands.

This is needed for the HTML version of the user manual.