Qt released some fancy classes to draw nice charts:
https://blog.qt.io/blog/2016/01/18/qt-charts-2-1-0-release/
With Qt 5.7 this will come bundled as a submodule. For now we can fetch it from github.
I'm not sure, whether we should wire it into bsd.qt.mk already or wait for the 5.7 release to do that.
This is based on the version by Marie Loise Nolden from our experimental Qt-5.7.1 ports.
p.s. shouldn't we convert the Qt-ports with s/DISTVERSION=/PORTVERSION=/?