Datepicker popover

[demshy]

Changing date picker so it makes use of Headless popover component for positioning according to available space.
Had to move trigger out of the Field element and made the popover stick to the right side of the field, where the trigger is.

[salamca]

• pressing the calendar button multiple times keeps opening the popover. it should toggle it.

• popover is a bit to close to the input

• there is a slight gap on the left end of the border below month. probably noone will notice, but if fix minor, could close the gap :)

• doesn't play nice inside log dialog

[demshy]

should be ok

• matched gap
• fixed the button to top instead of bottom and forgot about the label :)
• reopening fixed by passing {...rest} params in button
• removed margin that made the gap