Fixed: Usage of enum-type properties.
Merge commit '29ee6216e82ca8a8711c99ecbde2a9fbfd22cca9'

Conflicts:
	lib/QPersistence/src/cache.cpp
	lib/QPersistence/src/cache.h
	lib/QPersistence/src/dataaccessobject.cpp
	lib/QPersistence/src/objectlistmodel.cpp
	lib/QPersistence/src/objectlistmodel.h
	lib/QPersistence/src/relations.cpp
	lib/QPersistence/src/sortfilterproxyobjectmodel.h
	lib/QPersistence/src/sqldataaccessobjecthelper.cpp
	lib/QPersistence/src/sqldataaccessobjecthelper.h
	lib/QPersistence/tests/tst_cachetest.cpp