First implementation of getStyleInfo

getStyleInfo returns a simplified JSON format to make it easier to convert to CSS
Cool, done that. There are two possibilities though: the documentId is undefined i.e. no param was passed at all. I agree this should be caught. Then there is passing null to mean 'current document'. I'm not a fan of overloading the meaning of null as it makes it impossible to look at a stack trace and tell the difference between intentional/accidental passing of null. But before enforcing my own distaste for that I thought I'd check....