Use shared engine in ksplashqml
Review Request #125654 - Created Oct. 16, 2015 and submitted
As Martin G analysed in kscreenlocker_greet this cuts down a lot of time
on dual monitors.
Don't include struts in initial ksplash geometry
We initially set a ksplash window to a screen's availableGeometry then
monitored and screen->geometry. Using a mix is definitely wrong.
Won't make any practical difference as this is all started long before
plasmashell, but it's technically more correct.