Add line info to AST and type nodes. Add line info to errors of type module.

AST and Type nodes are decorated with line info during parsing.
Errors of type module now contain line info.
I agree this is a lot of repetition, but I am not sure how to fix it. A decorator is only a partial solution: Some grammar rules need decorating in only a few clauses. In addition, not all decorating is uniform; most of the times it is done by referencing a token, but sometimes we just copy another node's position.

I 'll think it over.