Better throttling

[gordonwoodhull]

As pointed out here: https://groups.google.com/forum/m/#!topic/dc-js-user-group/3AlQht_8Eqs

The current brush throttling is actually a debounce: it prevents more than one brushing event from happening in a time interval, but it also prevents any events from happening while there are events coming in at a higher rate, and then just fires the last one at the end.

What we really want is to fire redraws as fast as we can without them backing up. So we start the first redraw, then throw out all but the last event we get while that's happening, then start the next redraw, etc.

Also see #627: some would prefer having no redraws at all until the end of brushing.

[jefffriesen]

for reference for others reading this thread:
Difference between throttle and debounce

Lodash implementation of _.throttle:
https://lodash.com/docs#throttle
https://github.com/lodash/lodash/blob/master/lodash.src.js#L8438-L8455
https://github.com/lodash/lodash/blob/master/lodash.src.js#L7888

[Frozenlock]

Just learned about requestidlecallback from the video linked here : https://reactjs.org/blog/2018/03/01/sneak-peek-beyond-react-16.html

Perhaps there's something that can be done with it?