Check for empty values as well as missing values for better performance in the Views exposed widgets.

Invalid or empty dates need to replace the form array with an empty string. Also removing some code from date_api_sql that actually doesn't do anything.

Add some error trapping in case the parent dateObject is unable to make a date out of a string to avoid showing the user errors.

As long as I'm already moving all these files around, get all the views handling into its own module.

A partial date value array still must create a full ISO date or date_create() will not work correctly.