Use hello_world instead of the guessing_game
Move caret under the 'x' variabe
collections: Implement Eq for DList, RingBuf, TreeMap, TreeSet
collections: Implement Ord for DList, RingBuf, TreeMap, TreeSet
collections: Implement FromIterator/Extendable for BitvSet
auto merge of #16175 : EduardoBautista/rust/fix-guessing-game-appearing-early, r=steveklabnik

Solves: https://github.com/rust-lang/rust/issues/16162
auto merge of #16177 : nham/rust/collections_15294_eq_ord, r=alexcrichton

This implements:

 - Eq and Ord for DList, RingBuf, TreeMap and TreeSet
 - FromIterator and Extendable for BitvSet

cc #15294