Improve performance of `"*"`.

It may not be the common case, but it out to be the most performant that the user calls with POSIX time. It is worth exploring the performance of this common case at the expense of library size.

We test for numeric twice, once in the argument loop, and once again to see if we have found a date.

Also, we don't have to do the conversion tests, only for the date array type.