relax SVN archive

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!

All of the user function documentation tables now use the new Uf_tables singleton structure.

The special properties for the colour module tables (longtables and now spacing) have been added as
well.