Typeclass/interface implementation

[jwise]

This is a stub bug, tracking @marijnh's efforts in implementing typeclasses. Created so that I could link to it from another bug.

More detail: https://mail.mozilla.org/pipermail/rust-dev/2011-November/001010.html

[jwise]

Oops, tagged the wrong Marijn. Now tagging @marijnh.

[marijnh]

Latest proposal at https://github.com/graydon/rust/wiki/Interface-and-Implementation-Proposal

[boggle]

I like the direction this is taking, especially the unification of static type classes and the proposal for boxed existentials (interface, value).

Have added an idea on how to add delegation to the wiki.