collections: Move push/pop to MutableSeq

Implement for Vec, DList, RingBuf. Add MutableSeq to the prelude.

Since the collections traits are in the prelude most consumers of
these methods will continue to work without change.

[breaking-change]

1 files changed, 1 insertions, 0 deletions

diff --git a/src/libstd/io/signal.rs b/src/libstd/io/signal.rs
index d46f437cddd..c126866e715 100644
--- a/src/libstd/io/signal.rs
+++ b/src/libstd/io/signal.rs
@@ -20,6 +20,7 @@ definitions for a number of signals.
 */
 
 use clone::Clone;
+use collections::MutableSeq;
 use comm::{Sender, Receiver, channel};
 use io;
 use iter::Iterator;