Convert user manual from LaTeX to Sphinx markup
Integrate wiki information into the manual

The wiki pages were here: https://github.com/SoundScapeRenderer/ssr/wiki
Include AUTHORS in Sphinx documentation
Manual: proper Sphinx figure captions
Include Sphinx manual in build system
Manual: Fix minor typesetting issues
Fix figure references in text, add link to online manual
Add version number to PDF manual

... and a few other minor changes.