auto merge of #5255 : jbclements/rust/remove-parse-value-ident, r=graydon

After the removal of the "restricted keyword" feature in 0c82c00dc4 , there's no longer any difference between parse_ident() and parse_value_ident(), and therefore no difference between parse parse_path_without_tps() and parse_value_path().  I've collapsed all of these, removing the redundant functions and eliminating the need for two higher-order arguments.

src/libsyntax/ast.rs

@@ -105,6 +105,10 @@ pub struct Lifetime {
     ident: ident
 }
 
+// a "Path" is essentially Rust's notion of a name;
+// for instance: core::cmp::Eq  .  It's represented
+// as a sequence of identifiers, along with a bunch
+// of supporting information.
 #[auto_encode]
 #[auto_decode]
 #[deriving_eq]