top titlebar

I prepared the necessary things for a top bar with the class name and a slogan (configurable)

cc @chris for design feedback

the two i icons at the top are subject to change... the idea is to have (better icons and) the possibility to add a overlay or something with some background information when the icon is clicked
if we merge this already now, we should simply remove the is and do the correct implementation later; however the space for the icon(s) is already prepared

resolves #16 (closed)