Allow Singles to have a "Post Date" like Structures and Channels

[stevecomrie]

There's no real reason (that I can think of) why this shouldn't be a thing.

In fact, if you hack the template for editing a Single and insert the Post Date form controls from editing a Channel or Structure entry, everything saves and displays on the front end exactly as you would expect it to .

If Singles couldn't be disabled, then I could see the argument as to why not allowing a Post Date makes sense.

But if you can disable/enable them manually, then surely you can set them to be enabled at a certain time in the future instead of forcing a manual edit.

Could at least consider making it a configurable option to enable it.