Bump to 1.31.0 and bootstrap from 1.30 beta

src/libterm/lib.rs

@@ -50,7 +50,7 @@
 #![cfg_attr(windows, feature(libc))]
 // Handle rustfmt skips
 #![feature(custom_attribute)]
-#![cfg_attr(not(stage0), feature(nll))]
+#![feature(nll)]
 #![allow(unused_attributes)]
 
 use std::io::prelude::*;