Message 39159 - Python tracker

Logged In: YES 
user_id=21627

A note on the implementation strategy: it turned out that
communicating the encoding into the abstract syntax was the
biggest challenge. 

To solve this, I introduced encoding_decl pseudo node: it is
an unused non-terminal whose STR() is the encoding, and
whose only child is the true root of the syntax tree. As
such, it is the only non-terminal which has a STR value.