Remove module prefix from Qt includes in public headers
There is a minimal risk that someone somewhere has managed to rely on the full path, though any normal Qt usage by cmake or qmake should result in include dirs being imported and used with also the dir pointing to the very QtCore headers, so I consider such usage not really supported and are ready to break it.
246bbcc4 right before gave an example of an include that worked even if QtDBus was not linked officially (and thus with cmake the QtDBus include dir being pulled in), whereas -#include instead would have failed immediately and shown the use of a header from a module we did not know we were using (headers from), by looking at the link list.