S9 LIB  (string-split char string)  ==>  list

Split a string into substrings. CHAR is interpreted as a separator.
Return a list containing all coherent sequences of non-separating
characters contained in the given string.

(string-split #\space " to be  or  not to be ")
  ==>  ("to" "be" "or" "not" "to" "be")
