Summary

Currently, axis3d.Axis inherits from axis.XAxis which inherits from axis.Axis. This is a bit strange and possibly inconvenient. Especially if we think that the 3D stuff will make it into the main library at some stage.

Proposed fix

Rename axis3d.Axis to Axis3D.

One will have to check it there is anything in XAxis that is actually needed and then consider how to proceed. (One may guess that anything needed in XAxis is so generic that it can go in Axis since it then would be needed for YAxis as well?)

Possibly, one should also rename axis3d.XAxis to axis3d.XAxis3D etc. for consistency.