v0.5.0

Fix

• Potential overflow in copy_to_slice

Changed

• Increased minimum supported Rust version to 1.39.
• Bytes is now a "trait object", allowing for custom allocation strategies (#298)
• BytesMut implicitly grows internal storage. remaining_mut() returns
  usize::MAX (#316).
• BufMut::bytes_mut returns &mut [MaybeUninit<u8>] to reflect the unknown
  initialization state (#305).
• Buf / BufMut implementations for &[u8] and &mut [u8]
  respectively (#261).
• Move Buf / BufMut "extra" functions to an extension trait (#306).
• BufMutExt::limit (#309).
• Bytes::slice takes a RangeBounds argument (#265).
• Bytes::from_static is now a const fn (#311).
• A multitude of smaller performance optimizations.

Added

• no_std support (#281).
• get_*, put_*, get_*_le, and put_*le accessors for handling byte order.
• BorrowMut implementation for BytesMut (#185).

Removed

• IntoBuf (#288).
• Buf implementation for &str (#301).
• byteorder dependency (#280).
• iovec dependency, use std::IoSlice instead (#263).
• optional either dependency (#315).
• optional i128 feature -- now available on stable. (#276).