Charts shouldn't need network requests to filter their own data

[timwis]

When you select a bar, the chart you selected filters itself to only show that bar. Maybe we could just use highlighting from #222 to save a network request. And the filtered <path> on the DateTime chart doesn't quite align fully with the initial line anyway. I think v1 behaves this way for pie charts.

[timwis]

I've got DateTime not filtering itself, and instead using a <clipPath> to only show the selected range, but the tooltip still shows filtered amounts for the whole chart (when another filter is active). So a better wording of this issue would be that charts shouldn't make network requests to filter themselves.

[timwis]

Note that the table component will need a network request to filter itself (say, by searching).