Make QApplication::type() set by QGuiApplication.

Make QApplication::type() set by QGuiApplication.

QApplication::type used to be static and set by the
QApplicationPrivate constructors.

In QCoreApplication we have the new application_type that should take its place.
QApplication::GuiServer is deprecated (since it doesn't have any functionallity
any more with QWS being removed).

This change prepares QStyle to be called from a QQuickCanvase based application
that does not inherit the QWidget version of QApplication.

Change-Id: Ifbe992e25f1e5821fa047b6eb915f75fa675ab97
Reviewed-by: Paul Olav Tvete <paul.tvete@nokia.com>