Merge branch 'doc-build-debian' into 'master'

Doc: Add apt instructions to install dependencies on Debian

See merge request !154

Documentation/DeveloperHelpSources/building.docu

@@ -17,6 +17,13 @@ OpenFlipper.
 <li> QWT (>=6.0)  ( optional, used for histogram plottings, http://qwt.sourceforge.net/)</li>
 </ul> 
 
+On Debian, you can install the prerequisites this way (tested on Debian buster):
+
+<code>
+apt install cmake make g++ libeigen3-dev python3-dev qt5-default libqt5script5 libqt5scripttools5 libqt5svg5-dev libqt5quick5 libqt5x11extras5-dev libqt5help5 qtscript5-dev libqt5xmlpatterns5-dev libqwt-qt5-dev qttools5-dev qtdeclarative5-dev
+</code>
+
+
 \section bs Build System
 The build system uses cmake to generate all makefiles.