multiple files per page

So I think the solution here is something like this...

1. Add a markup indicator to associate code blocks within a page with a filename (this also allows the page "Foo" to generate "foo.c" without running afoul of sputnik's behaviour for ".")
2. Add a sputnik action that takes gives the code for file X from page Y (eg, Foo.code?file=foo.c)
3. Change the markup decoding to add a panel on the right-hand side listing the files within the page, and linking to the code action for each
4. If there're "foo.ext" files in git, combine them into a faux "foo.mdwn" page.