notes/kde-bindings--question-about-hello-cpp.u8: a question answered
use and init qtcore

This is best practice, as explained in
notes/kde-bindings--question-about-hello-cpp.u8
examples/hello: update call form of call-method[/safe]
call-method/classid+methidx: update call form
examples/hello: make 'qapp' with the instantiate method
examples/hello: make 'widget' with the instantiate method
examples/hello: call-method/safe was renamed to call-method-with-callbacks
examples/hello: style, structure