Include axis orientation in dimensions information

[tdudgeon]

The dimensions() function nicely provides lots of information about charts axes and I'm using this to persist settings between sessions. But I find that the orientation of the axis (min to max or max to min, which is set by double clicking on the header) is not included in this information and so if any axes are inverted this info is not persisted and gets reset.

So:

1. would it be possible to include this information in future
2. is there a way to get this info and an event to know when it is changed?

[syntagmatic]

Whatever the flip axis code currently does, it should do this: reverse the domain of the scale on the axis. This information would be persisted as part of the scale, eliminating the need for an array of flipped or inverted axes (or an extra property on the dimension object).

[timelyportfolio]

ref #265 (comment)