Base85 Operations

[PenguinGeorge]

To resolve #286.

This adds two new operations:

• To Base85
• From Base85

Both operations include three common alphabets for Base85:

1. Standard - also known as Ascii85, and is the standard alphabet for base85.
2. Z85 (ZeroMQ) - a "string safe" variant which doesn't use single or double quotes, backslashes, or other problematic characters.
3. IPv6 - alphabet used for encoding IPv6 addresses, as defined by RFC 1924.

The "To Base85" operation also has an "Include delimiter" option, which will add <~ and ~> at the start and end of the output, which is a standard used in Adobe PostScript.

Tests have also been added for these operations.

Example:

[n1474335]

Hi @PenguinGeorge, would you mind converting this to the new operation format then we can get it merged.

Thanks

[PenguinGeorge]

I have submitted a new pull request #340 for this.