maximum integer digits

[patch]

Implement the functionality supplied by the maximum_integer_digits attribute, which already exists as a stub. There doesn’t appear to be a symbol associated with this.

UTS #35, Part 3, §3.3:

If the number of actual integer digits exceeds the maximum integer digits, then only the least significant digits are shown. For example, 1997 is formatted as 97 if the maximum integer digits is set to 2.