Rewrote KService::hasServiceType() to not use KMimeType (for the kdecore/kio split):
* Split into hasServiceType() and hasMimeType()
* Use the trader offers for the case where the service come from ksycoca, which makes
those methods much faster (13 times faster according to callgrind!)
* Use the old implementation for the case of KServices created from full paths
or KConfig objects, but without support for mimetype inheritance. If we really
need this one day (which I doubt), we'll still have solutions (cf comment in code).