update the user guide

[thorade]

The User Guide pdf is created from rst source files, using Sphinx.
In the past, these files were hosted in a dedicated private repository,
but PR #116 moved the source files to the docs directory of this repository.

Some instructions on how to get started with rst and Sphinx are given in the ReadMe.rst file here:
https://github.com/UdK-VPT/BuildingSystems/tree/master/docs

The next step is now to update the users guide and tutorial!

[thorade]

Pull Requests should trigger a build, and broken builds should block the merging!
Is this possible with protected branches and status checks?
readthedocs/readthedocs.org#1340 (comment)

[thorade]

@nytschgeusen Can we move the models from
https://github.com/UdK-VPT/BuildingSystems/tree/master/BuildingSystems/Resources/Documentation/ExamplesUserGuide
to the main library?

[thorade]

The binary pdf file was previously stored in the repository,
but commit 27e4a85 removed it from the repository.
A backup of the old documentation pdf is here: UserGuide_BuildingSystems.pdf

[thorade]

Note: vector graphics give better quality than pixel graphics (where applicable).
Use image.* and Sphinx will use image.png or image.svg or image.pdf depending on output format
http://www.sphinx-doc.org/en/master/usage/restructuredtext/basics.html#images

• Dymola allows export as svg, the svg file can then be edited and converted to pdf using Inkscape.
• dymat+matplotlib allow export as pdf directly, for plotting results diagrams.