We should probalby warn when defining a method foo on {foo: int} etc.
This should reduce the amount of useless typevars that are allocated.
Issue #1227
Move the name of the bundle to the front, allow type parameters (not
handled yet), and add a 'for' keyword:
impl utils for int {
fn str() -> str { int::str(self) }
fn times(f: block()) { ... }
}