Configurable quotes

The transformers currently return both single (addDisplayName and quoteAttrName) and double quotes (JSON.stringify) in the transformed result, so it is impossible to enforce quote rules. I've added an option called useSingleQuotes that decides if double or single quotes should be used throughout. I may be missing other cases, but this seems to address the issues I have had.




This is not correct, `"\\"` for instance becomes `'\\"` if I'm reading it correctly. I could recommend having a look at my previous #1517 which has a very simple implementation.