new functions: similar_text() and round()

The function similar_text() and round() are now available for testing.

This calculates the similarity between two strings as described in Oliver [1993]. Note that this implementation does not use a stack as in Oliver’s pseudo code, but recursive calls which may or may not speed up the whole process. Note also that the complexity of this algorithm is O(N**3) where N is the length of the longest string.

Returns the rounded value of $val to specified $precision (number of digits after the decimal point). $precision can also be negative or zero (default).