1) Delete duplicate or unused images in Documentation/images directory
2) Add text to describe user manual viewer functionality
3) Add image to explain 2) above
4) Add text to explanation of TTS toolbar button (Thank you very much, Davide!)
5) Update image showing display of TTS toolbar button
Signed-off-by: Willem Ferguson <willemferguson@zoology.up.ac.za>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>