Fix ProgressHex mount blocking render for several seconds

[mvasigh]

Fixes #234

Seems that ProgressHexAnimator mounts to the anime timeline redundantly in a loop, where a single invocation does the same thing. This brings tl.add() runtime down to 42ms with the same profiler settings, down from 6000ms+

[pastelsky]

Good catch @mvasigh . I've felt the slowdown in response times as well after having added this. However, removing this loop changes the animation –

Before

After

We'll need a different way to solve this. Maybe instead of queuing up 50 iterations upfront, its best to add the next iteration in the onFinish (or similar) callback of the previous iteration – one at a time.

[mvasigh]

Good point! I assumed that the second portion of the animation is intended to loop (rather than just run 50 times) so I separated the two into different anime instantiations and return a Promise that resolves to the timeline.

Before:

After (showing both the first "half" and the timeline with looping animation):

However, since we are no longer adding multiple stages, seems like we don't need a timeline instance and should just loop the second portion? Should I just remove the use of timeline? (haven't worked with this lib before)