Make capture() idempotent.
Make capture() idempotent.

As long as you're the capturing layer. It's annoying to have to check whether
we're captured already in all the client code that just wants to capture an
interaction when a condition is met.

ruslansennov/playn2,tinkerstudent/playn,playn/playn,thecocce/playn-1,rachelharvey/playn,thecocce/playn-1,playn/playn,rachelharvey/playn,tinkerstudent/playn,longtaoge/playn,playn/playn,longtaoge/playn,ruslansennov/playn2