Update to rustc 1.17.0-nightly (b1e31766d 2017-03-03)

Closes #77

Squashed commit of the following:

commit f88e4dfa5a62f9d6e00ed0980b6fb6d41d36151c
Author: Chris Wong <[email protected]>
Date:   Tue Mar 7 20:54:54 2017 +1300

    Convert errant tabs to spaces

commit 65936ef
Author: Sander Maijers <[email protected]>
Date:   Mon Mar 6 17:15:20 2017 +0100

    Refactor to make more generic

commit dc16b66
Author: Sander Maijers <[email protected]>
Date:   Thu Mar 2 16:47:52 2017 +0100

    Adjust to make compatible with current `libsyntax`

    Was broken since rustc nightly 2017-03-01.

maud_macros/src/parse.rs

@@ -204,7 +204,7 @@ impl<'cx, 'a, 'i> Parser<'cx, 'a, 'i> {
             // ???
             _ => {
                 if let [ref tt, ..] = *self.input {
-                    parse_error!(self, tt.get_span(), "invalid syntax");
+                    parse_error!(self, tt.span(), "invalid syntax");
                 } else {
                     parse_error!(self, self.span, "unexpected end of block");
                 }
@@ -369,9 +369,7 @@ impl<'cx, 'a, 'i> Parser<'cx, 'a, 'i> {
                 self.shift(1);
                 bodies.push(tt.clone());
             },
-            [TokenTree::Token(sp, _), ..] | [TokenTree::Delimited(sp, _), ..] | [TokenTree::Sequence(sp, _), ..] => {
-                bodies.append(&mut self.match_body(sp)?);
-            },
+            [ref tt, ..] => bodies.append(&mut self.match_body(tt.span())?),
         }}
         Ok(bodies)
     }