Fix calibration metadata to use imglib2-realtransform

[ctrueden]

The imglib2-realtransform package is a robust transform-based way of supporting coordinate system transformations, including per-axis transformations but also much more.

We should retire the calibrated portions of the net.imagej.axis package, in favor of using imglib2-realtransform. There is probably code of value in net.imagej.axis that can be retooled in some way, but what we want to avoid is limiting ourselves to only per-axis calibration support, since it is not powerful enough for many use cases.

[ctrueden]

@axtimwalde @tpietzsch Maybe a good September hackathon effort?

[bogovicj]

@axtimwalde @tpietzsch @ctrueden
Jumping on this old issue. What do we think of this idea?

I have code like this all over the place that generates a RealRandomAccessible in physical units from image metadata.

I know at least @tischi would benefit from this too, and this is the place for it.
If we agree on what the api should be, I'd be happy to take lead on this (I'd hugely benefit).
Alternatively, I can get something preliminary started, point to a branch here, and then hear critiques.