Returns the CRS to use for the project when transforming 3D data,
or when z/elevation value handling is important.
The returned CRS will take into account verticalCrs(), e.g. by
returning a compound CRS consisting of crs() + verticalCrs().
This method may still return a 2D CRS, e.g in the case that crs()
is a 2D CRS and no verticalCrs() has been set for the project.
I.E. It is NOT guaranteed that the returned CRS will actually
be a 3D CRS, but rather it is guaranteed that the returned CRS
is **ALWAYS** the most appropriate CRS to use when handling 3D data.
If the project crs() is a compound CRS, then the CRS returned
by QgsProject::verticalCrs() be the vertical component of
QgsProject::crs(). Otherwise it will be the value explicitly
set by a call to setVerticalCrs().
The vertical crs is a persistent property of a project, which
is saved/restored to xml.
And expose through Project Properties elevation settings widget
This setting allows users to specify the upper and lower
elevation limits associated with the project. (I.e. its an
equivalent to QgsProjectTimeSettings::temporalRange)
The original workaround was only supposed to apply to QList/
QVector of QVariantMaps. By replacing them all in sip we
break mapping of signals defined in c++ which are emitted
by Python code.
Fixes exceptions after running processing algorithms in Qt6
builds.
