Add binary and other useful tests.

Base64 encoding for email/MIME was intended to provide a transport coding for binary data over email protocols designed for 7 bit ASCII text. Some examples would be sound, image or video attachments.  One of the files included in this merge requests adds some binary tests using UTF-16 encoded characters with higher codepoints than basic latin letters under utf-8 and some other encodings.  A few basic one byte binary tests are included as well.

Also included is a file with a test vector for an RFC dedicated to Base-N, including Base64 encoding, RFC4648.

Best Wishes ...