axes.m: reworks axes restacking for ML compatibility (bug #43282) * axes.m (restack_axes): New subfunction. * axes.m ("axes (prp/val)" form): restack annotation axes, only if it was already on top * axes.m ("axes (HAX)" form): let axes with "handlevisibility" == "off" be restacked also * annotation.m: ensure annotation axes is on top when drawing a new annotation.