Guarantee uniqueness of token types

Finally figured out a way to guarantee uniqueness of token types. It was
simple actually and makes that code simpler, more maintainable, and gave
me much more confidence that it was correct. A big score for easy
metaprogramming in dynamic languages.
Recognize insertion blocks in translator module
Do nothing (for now) with unknown tokens

in the translator module
Refactored translator to reduce duplication
Recognize variant block in translator module

The refactoring in the previous commit speeded up my development of the
translator module!