Add a [Link] button to the "Try CoffeeScript" interface

[banksJeremy]

(Replacing #1628.) This adds a button to the "Try CoffeeScript" interface which is a permalink to the current source code. Here's an example on my fork.

[michaelficarra]

I don't like the inline style, and the href value appears unnecessary.

[banksJeremy]

What is the correct way to make changes? Do I just add commits to this, or do I start a new request so as not to clutter the log?

[michaelficarra]

I'd like to see the src value in the fragment (referenced in 3 different places) pulled out and assigned to a descriptive variable. Also, something other than src may be more appropriate. Maybe try_cs_permalink? I know, it's a little long...

[michaelficarra]

Just push extra commits. They'll show up here between the comments.

[banksJeremy]

I still have the inline styles on the button, I'm not sure of the cleanest place to move them.

[michaelficarra]

I'm guessing you would put the style in a selector in /documentation/css/docs.css somewhere around the 260s.

[jashkenas]

Thanks -- this is great. Merged with some minor style (camelCase) tweaks.