lib: Import base64 at the top-level, and not in a module.

src/error.rs

@@ -1,13 +1,15 @@
 use std::convert::From;
 use std::io;
 
+use base64;
 use minidom;
 
 #[derive(Debug)]
 pub enum Error {
+    ParseError(&'static str),
     IoError(io::Error),
     XMLError(minidom::Error),
-    ParseError(&'static str),
+    Base64Error(base64::Base64Error),
 }
 
 impl From<io::Error> for Error {
@@ -21,3 +23,9 @@ impl From<minidom::Error> for Error {
         Error::XMLError(err)
     }
 }
+
+impl From<base64::Base64Error> for Error {
+    fn from(err: base64::Base64Error) -> Error {
+        Error::Base64Error(err)
+    }
+}