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.




Wouldn't it make more sense to introduce a helper (like quoteAttr) for all stringifying (should be used quoteAttr as well), rather than implement a slight variation of it at each use.