parser: Refactor coagulated binops as postfix operators

This allows them to intermingle more nicely with `Try`

src/ast/macro_matcher.rs

@@ -191,6 +191,8 @@ impl<A: Annotation> Match<A> for Pat {
             (Pat::Tuple(_), _) => false,
             (Pat::Slice(pat), Pat::Slice(expr)) => Match::recurse(sub, pat, expr),
             (Pat::Slice(_), _) => false,
+            (Pat::Alt(pat), Pat::Alt(expr)) => Match::recurse(sub, pat, expr),
+            (Pat::Alt(_), _) => false,
         }
     }
 
@@ -205,6 +207,7 @@ impl<A: Annotation> Match<A> for Pat {
             Pat::Rest(pat) => pat.apply(sub),
             Pat::Tuple(pats) => pats.apply(sub),
             Pat::Slice(pats) => pats.apply(sub),
+            Pat::Alt(pats) => pats.apply(sub),
         }
     }
 }