Improved text rendering in Qt 3D Studio

There are multiple customers asking for better font rendering. Major things missing are things like italic, bold etc. configs (instead of having to directly choose an italic font). Font cascades (allowing use of font that doesn't e.g. have a certain character, but being able to fall back to a font that then has that character for that particular character).

TODO: Write better description of all the requirements we've received on this.