Remove ByteOrder generic methods from Buf and BufMut (#187)

* make Buf and BufMut usable as trait objects

- All the `get_*` and `put_*` methods that take `T: ByteOrder` have
  a `where Self: Sized` bound added, so that they are only usable from
  sized types. It was impossible to make `Buf` or `BufMut` into trait
  objects before, so this change doesn't break anyone.
- Add `get_n_be`/`get_n_le`/`put_n_be`/`put_n_le` methods that can be
  used on trait objects.
- Deprecate the export of `ByteOrder` and methods generic on it.

* remove deprecated ByteOrder methods

Removes the `_be` suffix from all methods, implying that the default
people should use is network endian.

src/lib.rs

@@ -23,11 +23,11 @@
 //! example:
 //!
 //! ```rust
-//! use bytes::{BytesMut, BufMut, BigEndian};
+//! use bytes::{BytesMut, BufMut};
 //!
 //! let mut buf = BytesMut::with_capacity(1024);
 //! buf.put(&b"hello world"[..]);
-//! buf.put_u16::<BigEndian>(1234);
+//! buf.put_u16(1234);
 //!
 //! let a = buf.take();
 //! assert_eq!(a, b"hello world\x04\xD2"[..]);
@@ -92,8 +92,6 @@ mod bytes;
 mod debug;
 pub use bytes::{Bytes, BytesMut};
 
-pub use byteorder::{ByteOrder, BigEndian, LittleEndian};
-
 // Optional Serde support
 #[cfg(feature = "serde")]
 #[doc(hidden)]