infinite scale may occours if the qml scale binding sets an infinite scale.

Reviewed-by: Alessandro Portale

QMLObserver links against the library dynamically. User's apps can also
link to it statically, so that the app can be deployed with debugging
features to a device, without having to worry about library deployment.

This qmlviewer will be also the default one when opening qmlproject files
as the runconfiguration was changed too.

This adds a new "Design" mode that can be used to manipulate qml files
in a visual way. It will only get build if you have the declarativeui
module in Qt.

This is a squashed import from the Bauhaus project. Share & enjoy :)