Converted the endian structures to enumerations.

The BigEndian and LittleEndian structures were turned into enumerations
so that they could not be instantiated.

src/endian.rs

@@ -7,14 +7,6 @@ use ::converter::Converter;
 
 
 
-/// Handles serialization where the most
-/// significant byte is stored at the lowest address.
-pub struct BigEndian;
-
-/// Handles serialization where the most
-/// significant byte is stored at the lowest address.
-pub struct LittleEndian;
-
 /// Defines the current platforms endianess.
 /// This is can only be big endian or little endian.
 /// This library does not support a mixed endian setting.
@@ -30,6 +22,18 @@ pub type PlatformEndian = BigEndian;
 #[cfg(not(target_endian="big"))]
 pub type PlatformEndian = LittleEndian;
 
+/// Handles serialization where the most
+/// significant byte is stored at the lowest address.
+pub enum BigEndian
+{
+}
+
+/// Handles serialization where the most
+/// significant byte is stored at the lowest address.
+pub enum LittleEndian
+{
+}
+
 /// Create an enumeration of the different
 /// available endianesses.
 #[derive(Clone, Copy)]