Rename macro_escape to macro_use

In the future we want to support

    #[macro_use(foo, bar)]
    mod macros;

but it's not an essential part of macro reform.  Reserve the syntax for now.

src/libsyntax/parse/mod.rs

@@ -24,7 +24,8 @@ use std::num::Int;
 use std::str;
 use std::iter;
 
-#[macro_escape]
+#[cfg_attr(stage0, macro_escape)]
+#[cfg_attr(not(stage0), macro_use)]
 pub mod parser;
 
 pub mod lexer;