Support for the M! and d! format codes

[DirigoPete]

In release 2.1.0, code was added that causes the M! and d! format codes (which permit optional leading zeroes in months and days, respectively) to be replaced with MM and dd (two digits required):

dateFormat = dateFormat.replace(/M!/, 'MM') .replace(/d!/, 'dd');

I assume there was a reason for the replacement, but I'd really like to use those optional leading zeroes.