relax SVN archive

The graphics.fetch_icon() function argument 'format' can now be set to None.

This will return the file path without the extension.

Elimination of all duplicated chapter, section and subsection titles in the user manual.

This fixes bug #20185 (https://gna.org/bugs/?20185).

The HTML files for the user manual now have longer names - this is needed for removing the duplicates.

Fix for the duplicate title finding script - the LaTeX and HTML mode alternatives are no longer mixed up.

Improvements to the duplicate user manual title finding script.

Created a simple shell script to find duplicate titles in the relax user manual.

This is important for the HTML version of the manual as duplicated titles causes HTML pages to be
overwritten. For example all chapters, sections and subsections titled "Introduction" will load the
introduction.html file which will contain the text of the last section with that title!

Additions to the scripting section of the relaxation curve-fitting chapter of the user manual.

A small edit to the intro chapter for the multi-processor operation and logging.

Added some labelling to the infrastructure chapter of the user manual for referencing.

A number of updates and edits to the intro chapter of the user manual.

The model-free GUI screenshot has been shifted to the intro chapter in preparation for a full
tutorial with screenshots in the model-free chapter.