Also, get rid of two FIXMEs by refactoring some code, and moving the
call_expr check for be expressions into typeck, where it seems to
make more sense.
Introduce syntax like:
iface animal { ... }
class cat implements animal { ... }
to allow classes to implement ifaces. Casting classes to ifaces
is *not* yet supported. ifaces that a class implements are not
yet included in metadata.
The syntax is subject to change, and may go away completely if we
decide to use duck typing to relate classes with ifaces (see
http://smallcultfollowing.com/babysteps/blog/2012/04/10/declared-vs-duckish-typing/ )
Most could use the each method, but because of the hack used to
disambiguate old- and new-style loops, some had to use vec::each.
(This hack will go away soon.)
Issue #1619
Allow class methods to have type parameters (this is a change from the
original classes proposal).
Add test cases for classes with type parameters, and classes with methods
that have their own type parameters.
