Support cylinder information from Xdeep and Diving Log

This adds support for importing cylinder information from at least Xdeep
and Diving Log v 5.0.

Signed-off-by: Miika Turkia <miika.turkia@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Describe new CCR features in user manual

Signed-off-by: Robert C. Helling <helling@atdotde.de>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Adds advice on text strings to style guide

Signed-off-by: Tim Wootton <tim@tee-jay.demon.co.uk>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Update of the release notes for V4.3

This updates the V4.3 release notes.
1) The release notes text is moved into a newly-created directory ReleaseNotes
2) Three images for the release notes are created in a subdirectory within
   the ReleaseNotes directory.
3) Light editing of the complete text of the release notes was done.

Signed-off-by: willem ferguson <willemferguson@zoology.up.ac.za>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>