Arbitrary orientation of Volume layers in Volume.draw #162
Description
At the moment, Volume.draw works only for horizontal layers.
It would be good to modify it to draw arbitrarily oriented layers, for the future.
The only technical issue preventing this is that currently the layers have xyz placement but only xy spans. If all layer/panel classes returned xyz placement and xyz span, this could be generalized to arbitrarily oriented panels/layers in an Euclidean space.
Requires: changing the interface of layers/panels significantly, to return also a z span, and adapt the code to accept the new interface.