This submission has two functions compstr and compstrs (could have been incorporated in one function). The two function are the same except that one is for sorted arrays, and the other isn't.
The function searches for equal strings in the two arrays, and also gives the strings which appear only in one of the two string-arrays.
iequal gives any nx2 array for indices in S1 and S2 respectively for the equal strings. i1 and i2 point to strings only appearing in S1 and S2.
!!!This function is made only for string-arrays where no equal strings appear!!!