feat(ripple): Add programmatic ripple activation/deactivation.

[sgomes]

First stage in fixing #9

[traviskaufman]

One code suggestion and a few docs nits but besides that LGTM!

[traviskaufman]

What if instead of checking for e === null we added a boolean property isProgrammatic to the activationState object, and used that instead? e.g.

activationState.isProgrammatic = e === null;
// ...
const isPointerEvent = !this.activationState_.isProgrammatic && /* ... */;

[sgomes]

Good idea. Done.

[traviskaufman]

could we say "for interdependent interaction between components" instead of "for complex interaction between deeply tied components"?

[sgomes]

Done.

[traviskaufman]

could we say "which happens when the ripple surface is engaged via interaction, such as a mousedown or a pointerdown event instead of "which happens on a down event"? Also I'm not sure we need to talk about the visual representation as coming from a keyboard event; we can just say it "expands from the center" or something a bit less implementation-specific instead.

[sgomes]

Done.

[traviskaufman]

could we say "which happens when the ripple surface is engaged via interaction, such as a mouseup or a pointerup event instead of "which happens on an up event"?

[sgomes]

Done.

[sgomes]

Thanks, @traviskaufman! Will merge when build goes green.