Encodes/decodes base64 strings according to RFC 2045 which requires line lengths of less than 76 characters and illegal characters to be removed during parsing.

See the following links for reference:

• https://www.ietf.org/rfc/rfc2045.txt
• https://stackoverflow.com/questions/25710599/content-transfer-encoding-7bit-or-8-bit
• https://stackoverflow.com/questions/13301708/base64-encode-length-parameter