This release contains a refactoring of internal readers used for unmarshaling by the decoder.

• It speeds up varint decoding slightly by providing a methods ReadUvarint() and ReadVarint() directly in the reader.
• When using a plain decoder with a byte.Buffer, it will now use the sliceReader which is more efficient compared to the newly introduced streamReader.
• When using any other io.Reader it now checks if it also implements io.ByteReader and constructs an appropriate fallback if necessary.