Support for aggregating the Y axis instead of the X axis

[MatthewCollinsNZ]

Hi Team,

We have just come across your library as we are having some major performance issues with plotly and need to resample, however the graphing that we are doing is graphs with depth on the y axis, so we I am wondering if the library could add the ability to choose which axis is aggregated, so that we would be able to leverage the code for vertical graphs with large numbers of points as well.

a snip of our graphing is below, we are looking at around 500,000 data points on screen in the snip.

Cheers

Matt