Reduce refreshes and allow partial zoom control

[sjustason]

A couple of changes:

• Add new props that allow us to de-couple changes triggered by remote zoom, and the always updated internal state of visibleTime; This basically allows for partial control as opposed to the full control triggered with the use of visibleTime

I'd like to investigate the comparison in getDerivedStateFromProps:

    const forceUpdate = items !== prevState.items || groups !== prevState.groups

Since I'm not sure this comparison is always accurate and may be identifying changes when there are none, but that will be a separate ticket.

[JustinmClapperton]

Based on testing in the other PR. This library looks good as well for now. I know you mentioned you might have an idea about not using getDerivedStateFromProps but I assume you plan to do that in a future update.