Switch to purely namespaced enums

This breaks code that referred to variant names in the same namespace as
their enum. Reexport the variants in the old location or alter code to
refer to the new locations:

```
pub enum Foo {
    A,
    B
}

fn main() {
    let a = A;
}
```
=>
```
pub use self::Foo::{A, B};

pub enum Foo {
    A,
    B
}

fn main() {
    let a = A;
}
```
or
```
pub enum Foo {
    A,
    B
}

fn main() {
    let a = Foo::A;
}
```

[breaking-change]

1 files changed, 4 insertions, 0 deletions

diff --git a/src/libserialize/base64.rs b/src/libserialize/base64.rs
index f287fb99750..9b1e285431f 100644
--- a/src/libserialize/base64.rs
+++ b/src/libserialize/base64.rs
@@ -11,6 +11,10 @@
 // ignore-lexer-test FIXME #15679
 
 //! Base64 binary-to-text encoding
+
+pub use self::FromBase64Error::*;
+pub use self::CharacterSet::*;
+
 use std::fmt;
 use std::string;
 use std::error;