v1.0.0-alpha3

• component: throw error if mounted on invalid target
• store: throw error if no store found
• doc: add a tutorial
• hooks: set el on refs (from useRef) all the time, even if target is a component
• fix: component concurrent rendering issue
• fix: properly validates optional types in object props
• component: remove renderBeforeRemount option for mount (it always renders)
• component: expose scheduler instance