Tag support for nodes

[stalhandske]

It would be really nice to be able to add tags for nodes. Just ran into a situation where I wanted to use YarnSpinner's GetTextForNode to get the raw string from a node. This only works if the node has the tag rawText, so being able to add this without editing the file itself would be cool.

[radiatoryang]

I wanted to get autocomplete working before doing tag support, but that's probably a long way away (if ever), so instead I will just do barebones tag support... probably in november or december when I have time

[stalhandske]

Thanks so much for even considering this.