module for encoding and decoding of ascii85/base85 strings

 Convert::Ascii85 implements the Ascii85 (also known as Base85) algorithm for
 encoding binary data as text. This is done by interpreting each group of four
 bytes as a 32-bit integer, which is then converted to a five-digit base-85
 representation using the digits from ASCII 33 (!) to 117 (u).
 .
 This is similar to MIME::Base64 but more space efficient: The overhead is
 only 1/4 of the original data (as opposed to 1/3 for Base64).