Flowable.create with lambda as last parameter

[arekolek]

How about a function like:

object Flowables {
    inline fun <T> create(
        mode: BackpressureStrategy,
        crossinline source: (FlowableEmitter<T>) -> Unit
    ): Flowable<T> = Flowable.create({ source(it) }, mode)
}

That would let us have code like:

Flowables.create<Int>(BackpressureStrategy.BUFFER) {
    it.onNext(1)
    it.onNext(2)
    it.onNext(3)
}

Instead of:

Flowable.create<Int>({
    it.onNext(1)
    it.onNext(2)
    it.onNext(3)
}, BackpressureStrategy.BUFFER)

[thomasnield]

Sounds good. Can you put in a PR?