Investigate usage of cross-language actions

[kasbah]

Antlr seems to have some support for cross-language actions embedded within Grammars, though I can only find one reference to them an it's in the context of testing Antlr itself. If it is what I think it is then it could potentially save us a lot of repeated code across different languages.

[kasbah]

I added a comment to a related Antlr issue. Parrt's comment:

yeah that works for a small set of known things like printing.