docs: Stop using notrust

Now that rustdoc understands proper language tags
as the code not being Rust, we can tag everything
properly.

This change tags examples in other languages by
their language. Plain notations are marked as `text`.
Console examples are marked as `console`.

Also fix markdown.rs to not highlight non-rust code.

src/librustdoc/html/markdown.rs

@@ -168,7 +168,8 @@ pub fn render(w: &mut fmt::Formatter, s: &str, print_toc: bool) -> fmt::Result {
                     slice::raw::buf_as_slice((*lang).data,
                                            (*lang).size as uint, |rlang| {
                         let rlang = str::from_utf8(rlang).unwrap();
-                        if rlang.contains("notrust") {
+                        let (_,_,_,notrust) = parse_lang_string(rlang);
+                        if notrust {
                             (my_opaque.dfltblk)(ob, &buf, lang,
                                                 opaque as *mut libc::c_void);
                             true