std: Rename {Eq,Ord} to Partial{Eq,Ord}

This is part of the ongoing renaming of the equality traits. See #12517 for more
details. All code using Eq/Ord will temporarily need to move to Partial{Eq,Ord}
or the Total{Eq,Ord} traits. The Total traits will soon be renamed to {Eq,Ord}.

cc #12517

[breaking-change]

src/test/run-pass/expr-match-struct.rs

@@ -23,7 +23,7 @@ fn test_rec() {
 #[deriving(Show)]
 enum mood { happy, sad, }
 
-impl Eq for mood {
+impl PartialEq for mood {
     fn eq(&self, other: &mood) -> bool {
         ((*self) as uint) == ((*other) as uint)
     }