v2.0.0-RC12: Add full suite of base64 functions to IDML (#20)
* Add full suite of base64 functions to IDML These can be called on strings as suffixes and include: * `base64encode` * `base64decode` * `base64mimeEncode` * `base64mimeDecode` * `base64urlsafeEncode` * `base64urlsafeDecode` Decoders will fail gracefully and short circuit if the input is not valid.