Ability to choose easing curve

This is really awesome, thanks! One minor feature request - is there a way to change the transition easing curve? You can change the durations, but the easing curve appears to be hard-coded to easeExpInOut which I find a bit "snappy". I think this is the relevant code:

function newCubeLayer(presenter, config, cubeData, highlightColor, lightSettings, lightingMix, interpolator) {
    const getPosition = getTiming(config.transitionDurations.position, easeExpInOut);
    const getSize = getTiming(config.transitionDurations.size, easeExpInOut);
    const getColor = getTiming(config.transitionDurations.color);

Just needs a config.transitionCurve or something too.

Start at the newCubeLayer function and inspect how config.transitionDurations and getTiming currently supply easing. Make the transition easing configurable instead of hard-coded to easeExpInOut, while preserving the existing duration and color behavior. Done means callers can choose the easing curve through configuration.