relax SVN archive

Complete rewrite of the docs.latex.fetch_docstrings module (accidentally partly committed at r16596).

This is a significant simplification for the creating of the user function documentation within the
user manual. Some of the long list of changes include:

- The file docs/latex/fetch_docstrings.py is no longer an executable script and now operates solely
as a Python module.

- All of the original docstring section parsing code has been eliminated. The searching for user
functions in the prompt UI namespace has been replaced

- The new user function definitions are directly used and the documentation for each user function
section generated via the self.build_*() methods.

- The complicated ascii table parsing and rebuilding into a LaTeX table has been eliminated.

- The self.write_*() methods have been created for building the various sections of the user
function documentation (paragraphs, verbatim text, prompt examples, lists, itemised lists, and
tables).

- Tables are no longer duplicated, triplicated, etc. Instead a reference to the first instance of
the table is inserted. This is a significant space saver, as one of the copies of the multi-page
X11 colour table is removed.

Renamed the Uf_tables.add_table() 'title' arg to 'caption', and added the new 'caption_short' arg.

The name change is fairly logical, as this is a caption. The 'caption_short' arg will be used for
the list of tables in the LaTeX user manual.

The Molmol colour table is no longer a longtable.

The prompt UI table creation is now using the Table.spacing variable for adding empty lines between rows.

Fixes for the prompt UI construction of the tables.

The top line was sometimes one '_' character too long. Now the correct table width is calculated as
it may not always match status.text_width.

The Monte Carlo description now uses an itemised list for the listing of the steps involved.

The prompt UI help string construction code is now handling the new Uf_tables singleton.

Added a check to Uf_tables.get_table() to make sure that the table corresponding to the label exists.

Fixes to the calls to Desc_container.add_table() in some user functions.

Added a check to Desc_container.add_table() to make sure the label is a string!