Axes should have a "position" argument

[aendra-rininsland]

As per the discussion in #759, the y2 axis is meant to be in addition to y (i.e., when there's a need for multiple axes), but using y2 is the only way of getting that axis on the right-hand side. As such, as a position option for each axis would be helpful.

[aendra-rininsland]

@masayuki0812 I'm working on a pull request for this, but need a bit of guidance. How should position be treated if the axes are rotated? Should position just be ignored? Translated (I.e., "left" becomes "bottom", "right" becomes "top")?

[masayuki0812]

@Aendrew Thanks for working on this. I think it should be ignored at this moment because it seems a little bit confusing and there would be not so much use case to translate (rotate dynamically).

[aendra-rininsland]

@masayuki0812 Sounds good! I think my PR won't merge at this point anyhow, so I'll just close that.