Date picker imrprovements

[olivr70]

I use NLP everyday, thanks a lot for the great work.

I recently discovered Date picker, which is the best option to insert timestamps for the time being.

Two possible improvements :

• intialize the Date field from the current selection.
• handle a history of recent formats

They would allow to correct date expression which is not detected (instead of retyping it). Also useful to change the date/time format of valid date