This revision adds a CodeGeneratorForQml class, that creates javascript code out of the QML-IR and utilizes PureJavaScriptGenerator to generate code for the js-snippets.

I decided to write a new code generator, because I the output format is completely different to what we used to have. Especially it is incompatible with our runtime. Instead it is meant to be used with the existing qmlweb1-runtime. It is more promising to use that and improve step by step. That means, the current output format, brings no advantages over interpreting (except of not needing to load the parser), but it works already.