Comments, minor refactoring, clean up wording of error messages

src/test/compile-fail/private-method.rs

@@ -1,4 +1,4 @@
-// error-pattern:Call to private method not allowed
+// error-pattern:call to private method not allowed
 class cat {
   priv {
     let mut meows : uint;

src/test/compile-fail/selftype-traittype.rs

@@ -3,7 +3,7 @@ trait add {
 }
 
 fn do_add(x: add, y: add) -> add {
-    x.plus(y) //~ ERROR can not call a method that contains a self type through a boxed trait
+    x.plus(y) //~ ERROR cannot call a method whose type contains a self-type through a boxed trait
 }
 
 fn main() {}

src/test/compile-fail/trait-test-2.rs

@@ -5,5 +5,5 @@ impl of bar for uint { fn dup() -> uint { self } fn blah<X>() {} }
 fn main() {
     10.dup::<int>(); //~ ERROR does not take type parameters
     10.blah::<int, int>(); //~ ERROR incorrect number of type parameters
-    (10 as bar).dup(); //~ ERROR contains a self type
+    (10 as bar).dup(); //~ ERROR contains a self-type
 }