Currently, it seems easier to upload the diagram images to git than to
try to make the image generation script work with out of the tree builds
and other corner cases.
This means, however, that one must activelly remember to update msc
diagram files, run the script and re-add new png files, if those ever
need to be updated. To raise awareness to that, a watermark was added
to the diagram images.
Also removed configuration steps that added mscgen as dependency
(locally and for workflow builds and readthedocs).
Moved devguide dir into userguide dir.
Since the devguide is now incorporated as the last chapter of the
userguide, removed build and configuration files from the devguide
dir, as these are no longer needed.
Task #4909
Add the missing manpages and the corresponding Sphinx configuration
for the command line tools `suricatasc` and `suricatactl`.
Closes redmine ticket #884.