Added table of contents

[Chidwan3578]

I have implemented a Table of Contents (TOC) for the documentation generated by
libodd.xsl. Below is a summary of the changes:

1. XSLT Enhancements in libodd.xsl
   New Parameter: Added odd:toc (boolean, defaults to true) to toggle the TOC.
   TOC Logic: Created a dedicated odd:toc template and mode that recursively scans for tei:div elements containing a tei:head.
   Anchor Integration: Links in the TOC use the same anchor logic as the main content (targeting the section's xml:id or a generated ID), ensuring seamless navigation.
   Unified Layout: Integrated the TOC into the html:content template so it automatically appears at the top of the generated documentation.

2. Modern Styling in documentation.css
   Layout: Added a stylized .toc container with a light background and subtle borders to differentiate it from the main content.
   Hierarchy: Styled nested lists to clearly represent the document structure.
   Interactivity: Added hover effects to TOC links for better user experience.

Closes issue #77

[lueck]

Your code looks good. However, there's one thing, I'd ask you to change: Though your idea to introduce a stylesheet parameter to toggle the toc on/off is consistent, we should leave it to the processed content, if there's a toc or not. TEI has specified a PI-like element named <divGen>. See https://tei-c.org/release/doc/tei-p5-doc/en/html/DS.html#DSVIRT

So, please remove the stylesheet parameter and its evaluation. Instead, add a template in mode text:text that matches div[@type eq 'toc'] and let it generate a toc in the mode that you introduced.

You may ask yourself, which divisions to process from a <divGen> element. All in //text/body? All the <divGen>'s sibling divisions and their descendants? All the <divGen>'s following sibling devisions and their descendands? Your solution may even depend on the ancestors of the <divGen>: Is it nested in //text/body or in the front matter (//text/front) or back matter (//text/back) of the document? You may take the content model of div-like elements into account. You can even change select="//body" in line 100 of libodd.xsl, if you think that it should be different.

I'm sure, you find a consistent solution.

I've just pushed commit 0650626 for an example is usage of <devGen>.