Now the dialogs use a copy of the ramp, and the edited
ramp is retrieved by calling ramp() on the dialog after
it is executed.
Avoids pointer lifetime issues by storing and working
on a ramp pointer which the dialog does not have ownership
on.
Also fix a bunch of leaks relating to cloning color ramps.
QgsVectorColorRamp -> QgsColorRamp
QgsVectorGradientColorRamp -> QgsGradientColorRamp
QgsRandomColors -> QgsRandomColorRamp
QgsRandomColorRamp -> QgsLimitedRandomColorRamp
QgsVectorColorBrewerColorRamp -> QgsColorBrewerColorRamp
These color ramps are used throughout all of QGIS (not
just in vector symbology) and the current names are
misleading.
