Date-Field: Support query language#269

It would be very handy if the min and max properties of the date/time field supported the query language in order to limit the field by dynamically generated dates, instead of hardcoding them.

What makes this so complicated is that you would expect those limits then to react on other content changes. E.g. in field B querying date field A as min. That won’t be possible before we move the content changes from localStorage to the server.