* Use horizontalAdvance
* Remove unused code
* Hide some warnings from Qt code
* Remove message for _SILENCE_TR1_NAMESPACE_DEPRECATION_WARNING
* Use CMP0077 NEW
* Move roff libraries to folder Thirdparty
* avoid operator()==
* Remove cmake_minimum_required and set version to 3.15
* Avoid calculating results many times for each change.
* Avoid drawing spurious contour lines when results are undefined.
* Add aggregation type to legend header (#3594).
* Rebased to the C-code by Bourke himself to avoid the sneaky little requirement
added by Nicholas Yue that only allows redistribution with explicit permission.