QQuickWindow cleanup: Remove forceRendering flag

forceRendering was introduced for QQuickWidget, but QQuickWidget
now has full control of when the rendering functions are called. It
makes more sense to not call the QQuickRenderControl functions, than to
set a flag on QQuickWidget that decides whether those functions have any
effect.

Change-Id: I69819b13000120c04cecd1a467c08e8df9330df8
Reviewed-by: Gunnar Sletta <gunnar.sletta@jollamobile.com>
networkaccessmanagerfactory example: introduced QCommandLineParser

Change-Id: I6385ee0c33a0a8cb411dbbdf5f6ea10f5ebde1a5
Reviewed-by: Andrew Knight <andrew.knight@digia.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
networkaccessmanagerfactory example: Fixed build with QT_NO_NETWORKPROXY

Change-Id: I803dd555961420b8189f36e1978a3fb65ab4d2a0
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Andrew Knight <andrew.knight@digia.com>