as it turns out, "almost" the whole codebase compiles in C++17 mode.
with the exception of two metaprogramming-related problems:
- our "duck detector" for STL containers does not trigger anymore
- the Metafunction to dissect Function sigantures (meta::_Fun) flounders
seems to work surprisingly well...
the diff application poceeds in the GUI up to the point
where the TrackPresenter need to be inserted into a two-fold display context
