Multi-axis goniometer needs axes= not axis= (cctbx#730)

* Raise an error if the user's PHIL overrides contains geometry.goniometer.axis
and the reference goniometer is multi-axis. In that case, the full
geometry.goniometer.axes must be set instead.

Fixes cctbx#729

newsfragments/730.bugfix

@@ -0,0 +1 @@
+Raise an error if ``geometry.goniometer.axis=`` is set with a multi-axis goniometer. In that case ``geometry.goniometer.axes=`` must be set instead.

src/dxtbx/model/goniometer.py

@@ -243,6 +243,10 @@ def from_phil(params, reference=None):
             raise ValueError("Only one of axis or axes should be set")
         if reference is not None:
             if isinstance(reference, MultiAxisGoniometer):
+                if params.goniometer.axis:
+                    raise ValueError(
+                        "All axes must be set for a multi-axis goniometer, not just axis"
+                    )
                 goniometer = GoniometerFactory.multi_axis_goniometer_from_phil(
                     params, reference
                 )