diagram → symbology Relation

File in src/core/diagram	Includes file in src/core/symbology
qgshistogramdiagram.cpp	qgslinesymbol.h
qgshistogramdiagram.cpp	qgssymbollayerutils.h
qgsstackedbardiagram.cpp	qgslinesymbol.h
qgsstackedbardiagram.cpp	qgssymbollayerutils.h