Replace by custom implementation, with the ultimate goal to
remove the QtCharts module. This doesn't yet display axis
titles or a grid.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
z-values determine the order in which objects on the chart are
painted. To reduce chaos, collect all z-values in a header file.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
