Implicit id for Router

[zsoltk]

Right now Router needs an explicit unique id for back stack store/retrieval from parent. It would be nice to make this implicitly without having to ask client code to define id.

[mvarnagiris]

So if you assume that users will use different sealed class per Router, then you could do something like this:

@Composable
inline fun <reified T: Any> Router(defaultRouting: T, children: @Composable() (BackStack<T>) -> Unit) {
    val contextId = T::class.java.name
    ...
}

Or

@Composable
inline fun <reified T: Any> Router(defaultRouting: T, contextId: String = T::class.java.name, children: @Composable() (BackStack<T>) -> Unit) {
    ...
}

[zsoltk]

That's a great idea, thanks! Opened #8 for it if you'd like to review.

[mvarnagiris]

Looks good!