[validate] Better ISO date and time validation

[DThrasher]

I have a few suggestions for enhancing the ISO date and time RegEx expressions. I modified a few examples I found on ​http://regexlib.com. The current dateISO validator allows nonsensical dates like 2008-67-87.

ISO date
^(\d{4})\D?(0[1-9]|1[0-2])\D?([12]\d|0[1-9]|3[01])$

ISO time
^([01]\d|2[0-3])\D?([0-5]\d)\D?([0-5]\d)?\D?(\d{3})?$

ISO offset
^([zZ]|([\+-])([01]\d|2[0-3])\D?([0-5]\d)?)?$

ISO date and time
^(\d{4})\D?(0[1-9]|1[0-2])\D?([12]\d|0[1-9]|3[01])(\D?([01]\d|2[0-3])\D?([0-5]\d)\D?([0-5]\d)?\D?(\d{3})?)?$

ISO Date, time and offset (the works)
^(\d{4})\D?(0[1-9]|1[0-2])\D?([12]\d|0[1-9]|3[01])(\D?([01]\d|2[0-3])\D?([0-5]\d)\D?([0-5]\d)?\D?(\d{3})?([zZ]|([\+-])([01]\d|2[0-3])\D?([0-5]\d)?)?)?$

[joern]

Providing a "complete" date method isn't feasible, therefore you have to write your own custom method for specific date formats.