- for Qt 5.15: added missing #include statements that became necessary since Qt 5.15
- for Qt 5.15: fixed use of several deprecated functions
- for Qt 5.15/6: removed usage of QMatrix
- some reorganizations into different files
- additional options for graph filling (color gradients, textures, ...) as provided by QBrush
- PREPARATIONS: added a general feature to JKQTPPlotElement which allows to show a graph in a highlighted state (if supported by the derived graph class!)
- JKQTPXYParametrizedScatterGraph: added functors to transform column values into symbol type+size and line-width to give even more control
- JKQTPStepHorizontalGraph has been renamed to JKQTPSpecialLineHorizontalGraph (vertical variants also) and have gained additional features (baseline for filling and drawing of symbols)
- filled curve graphs (e.g. JKQTPSpecialLineHorizontalGraph) are now merely a specializedly initialized JKQTPSpecialLineHorizontalGraph