Add axis autoscaling

[apalchys]

It would be great if PlotlyJS could autoscale an axis depending on the current data on the screen.

The idea is as soon as you change visible data range, you don't care what is outside of it and just want to see the auto-scaled chart.
I've implemented auto-scaling for Y axis and here is the demo: https://codepen.io/plotly-demo/pen/JOERgj. Try to change visible range or zoom in/out using mouse/touchpad (the implementation based on dragTail function)

Example of usage:
Plotly.newPlot('myDiv', data, layout, { autoscaleYAxis: true })

My branch & commit: apalchys@2afdb22

Could you please look into it and let me know what do you think? Would it be useful addition to the library?

[etpinard]

You mean something similar to #387 ?

[etpinard]

See also #1876 for more possibly-related thoughts on the topic.

[apalchys]

Sorry, I missed the #1876 issue. As far as I understand, my issue is exactly like this comment.

The main goal is dinamically (after interactions) autoranging one axis based on only the visible data.

[alexcjohnson]

Yes, this will definitely be included when we address #1876 - closing it here, @apalchys feel free to contribute to the discussion over there.