S9 LIB  (string-translate string1 string2 string3)  ==>  string

Translate STRING1 by replacing each instance of a character
that occurs in STRING2 by the character at the corresponding 
position in STRING3. STRING-TRANSLATE does not alter STRING1
but returns a fresh string.

(string-translate "a:b:c" ":" "-")  ==> "a-b-c"

(string-translate
  "hello, world!"
  "abcdefghijklmnopqrstuvwxyz"
  "nopqrstuvwxyzabcdefghijklm")     ==>  "uryyb, jbeyq!"
