Utilize fewer reexports

In regards to:

https://github.com/rust-lang/rust/issues/19253#issuecomment-64836729

This commit:

* Changes the #deriving code so that it generates code that utilizes fewer
  reexports (in particur Option::* and Result::*), which is necessary to
  remove those reexports in the future
* Changes other areas of the codebase so that fewer reexports are utilized

src/libstd/ascii.rs

@@ -19,7 +19,8 @@ use core::kinds::Sized;
 use fmt;
 use iter::IteratorExt;
 use mem;
-use option::{Option, Some, None};
+use option::Option;
+use option::Option::{Some, None};
 use slice::{SlicePrelude, AsSlice};
 use str::{Str, StrPrelude};
 use string::{String, IntoString};