[CAS 1284] Validate and adopt CAS3 protocol rev

- added reference implementation section 1.2
- added URI overview table
- minor fixes
- prepare for pandoc TOC support
- Updated README.md
- avoid build failure due to missing license header in generated spec html file using pandoc template.
- fixed line lengths in PDF files (GitHub markdown linebreak behavior differs from all other MarkDown flavors)
- removed escape chars.