Implement opt-in fallback to native rendering for text in QtQuick 2

Especially for Windows, but also for FreeType with some level of hinting turned on, there should be a way for the user to force the use of hinted fonts (native rendering) instead of the default distance field rendering. This can be a QML attribute on the Text/TextEdit/TextInput elements. The attribute should be documented as ideal for "old style" native look-and-feel interfaces, and that it should be avoided for interfaces that require fluid animations and scalability.

The glyph node for this is already implemented and only needs to be exposed through API to the user somehow.