add the filename in the warning message

[Roilan]

As I'm building out a email template system with this module, I've noticed that warning message doesn't specify where it comes from. At the moment, we assume everything is one giant component, which we shouldn't.

I'm currently digging through module.parent but if you have a better way / idea of finding the root source, please share!

[chromakode]

Trying to understand the use case here -- do you want to know that this warning is coming from react-html-email, or the exact file the warning came from? I think changing the text to be like "Warning (react-html-email):" would be a good idea, but I'm a little hesitant to add the complexity of resolving the filename.

I haven't seen other modules behave like this; for instance React will also output warnings without a mention of their origin file. I wonder if this is something you could implement more generally for your application purposes by monkeypatching console.warn/console.log to inspect the stack?