REQ: make legend optional

[rrozema]

I have a lot of devices, making the legend taking up a large part of the card. So large even that on my mobile devices only the last items on the legend are shown: nothing of the chart is visible. But even on larger screens like my pc, the chart is relatively small. Can we make the legend optional? Automatically hiding the legend when insufficient room would remain to show the chart, manually disabling it using a setting or showing only a subset of the items, all are acceptable solutions to me.