Comment/Message Preview Support

[smoak]

Uses api controller for comment/message preview support.

[spladug]

This should be done entirely client side, not via a roundtrip to the server.

[smoak]

I thought reddit has a customized version of markdown. Earlier before this patch I submitted a patch for comment preview support using showdown (markdown in JavaScript). I asked on IRC about it and the general consensus was that since reddit has a customized version of markdown it wouldn't be so great as a client side script.

[spladug]

We use discount as our
Markdown implementation. We do turn off several features (such as images)
but that should be the only customization needed. I'm not sure why your
previous request was rejected. I definitely feel that roundtripping for
markdown is not the right way to do it. We will be getting a frontend
developer very soon and I'll have him take a look. Thanks and sorry for the
trouble :)