Grid: Make it easier to create Bento Box layouts using auto mode

[noisysocks]

I’d expect the Auto mode to automatically adjust the position of items inside and adjust their height and position to fill all available space. For instance, if there are three items in a column, I’d expect them to be positioned one beneath another and scale automatically to fill available space (unless they have a fixed height).

The same goes for width: if all items are set to fill available, the columns would stretch proportionally. If at least one item has a fixed width and other items are set to auto, it’d define the width of the entire column.

(Thanks @jarekmorawski for sharing this feedback.)