path2: Remove Path::normalize()

There are no clients of this API, so just remove it.

Update the module docstring to mention normalization.

src/libstd/path/mod.rs

@@ -43,6 +43,10 @@ Option<&str> with `.as_str()`. Similarly, attributes of the path can be queried
 with methods such as `.filename()`. There are also methods that return a new
 path instead of modifying the receiver, such as `.join()` or `.dir_path()`.
 
+Paths are always kept in normalized form. This means that creating the path
+`Path::from_str("a/b/../c")` will return the path `a/c`. Similarly any attempt
+to mutate the path will always leave it in normalized form.
+
 When rendering a path to some form of display, there is a method `.display()`
 which is compatible with the `format!()` parameter `{}`. This will render the
 path as a string, replacing all non-utf8 sequences with the Replacement

src/libstd/path/posix.rs

@@ -349,7 +349,7 @@ impl Path {
 
     /// Returns a normalized byte vector representation of a path, by removing all empty
     /// components, and unnecessary . and .. components.
-    pub fn normalize<V: Vector<u8>+CopyableVector<u8>>(v: V) -> ~[u8] {
+    fn normalize<V: Vector<u8>+CopyableVector<u8>>(v: V) -> ~[u8] {
         // borrowck is being very picky
         let val = {
             let is_abs = !v.as_slice().is_empty() && v.as_slice()[0] == sep;

src/libstd/path/windows.rs

@@ -697,13 +697,6 @@ impl Path {
         Some(self.repr)
     }
 
-    /// Returns a normalized string representation of a path, by removing all empty
-    /// components, and unnecessary . and .. components.
-    pub fn normalize<S: Str>(s: S) -> ~str {
-        let (_, path) = Path::normalize_(s);
-        path
-    }
-
     /// Returns an iterator that yields each component of the path in turn as a Option<&str>.
     /// Every component is guaranteed to be Some.
     /// Does not yield the path prefix (including server/share components in UNC paths).