bug: Import declaration conflicts with local declaration of 'RectPosition'.

[davidquintard]

Hi, in latest version ("@fivethree/core": "^0.9.6",):
I've got following error:

ERROR in node_modules/@fivethree/core/lib/animations/tween.d.ts:1:10 - error TS2440: Import declaration conflicts with local declaration of 'RectPosition'.

import { RectPosition } from './tween';