cross.icn: Program to display intersection of words

   This program takes a list of words and tries to arrange them
in cross-word format so that they intersect. Uppercase letters
are mapped into lowercase letters on input.  For example, the
input

        and
        eggplants
        elephants
        purple

produces the output
     +---------+
     | p       |
     | u e     |
     | r g     |
     | p g     |
     |elephants|
     | e l     |
     |   and   |
     |   n     |
     |   t     |
     |   s     |
     +---------+

Diagnostics: The program objects if the input contains a nonal-
phabetic character.

Comments: This program produces only one possible intersection
and it does not attempt to produce the most compact result.  The
program is not very fast, either.  There is a lot of room for
improvement here. In particular, it is natural for Icon to gen-
erate a sequence of solutions.