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.




As far as I gather, the goal here is to replace every double quote that has not been escaped by JSON.stringify. The solution might actually be as easy as replacing the first and last characters, but I would want some feedback on that.

`"\\"` ends up being `'\"\\\"'`, which matches the behavior of #1517 with single quotes, as `'\\'` yields `'\'\\\''`. You have to escape one way or the other, and it makes sense to me that it preserves the result from JSON.stringify. Again I would like some feedback on that.