Overrides the equals method of the Object class
alph1.equals(alph2) returns true iff the arrays
alph1.ranges and alph2.ranges have the same lengths
and alph1.ranges[k] == alph2.ranges[k]for all k.
To find the find the keyword we break the cryptogram into
keyLen monoalphabetic cryptograms, each of which is obtained
by a Caesar shift from the standard alphabet.