Fix a bug, don't trigger onMoreAsked when adapter has no data or visi…

[doubleDragon]

Hi, i found two problem when using SuperRecyclerView.
First, there is no necessary to trigger api{#link onMoreAsked()} when adapter has no data or visibleItemCount equal totalItemCount, i have fixed in my fork project from you repo.
Second, i suggest you invoke api{#link processOnMore()} when scroll state equal RecyclerView.SCROLL_STATE_IDLE, because sometimes api{#link onMoreAsked()} always trigger loadingMore after scroll down.My suggest code like below:

@OverRide
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
super.onScrollStateChanged(recyclerView, newState);
if(newState == RecyclerView.SCROLL_STATE_IDLE) {
processOnMore();
}
}

[Malinskiy]

@doubleDragon Hi! Unfortunately if you do it this way there will be an edge case on initial start of view where you set the adapter with small number of items (not enough to fill in the screen). In this case I'd like to fetch more, but if you handle scroll state and data your way it won't call onMoreAsked.

But for the adapter case that is not set - feel free to create a PR for that, I'll merge it.

Let me know what you think