v1.0.0-rc.166 (#76)

* `rugnux --mode calibration` writes `<prefix>.json` beside the `.poni`, whose `dataset_settings` member is a `jfjoch_broker` `dataset_settings` body as it stands.
* `rugnux` and `jfjoch_viewer` read PILATUS miniCBF sweeps natively, without conversion.
* Masters written by other facilities open, including Eiger 1.x and third-party NXmx variants.
* `rugnux` measures the beam centre on every run, and indexes with it when the file's value indexes nothing.
* A detector swung out on a 2theta arm is placed where the file says it stands, and the calibration can hold the tilt fixed.
* `rugnux` writes the unmerged MTZ by default, and a P1 merge beside it, so a wrong space group can be re-merged without reprocessing.
* Significant improvements to symmetry handling in `rugnux`: the lattice, the point group, the setting and the systematic absences.
* The `rugnux` report gives the resolution the CC1/2 fit reached, beside the range the reflections were written to.
* The `rugnux` report gives the twinning statistics measured before the space group was decided, beside the ones measured after.
* The `rugnux` report gives the strong-direction diffraction limit, and warns when CC1/2 is not monotone with resolution.
* `rugnux` ranks screw axes on the evidence their absences carry, rather than on how many control reflections a candidate happens to have.
* Twinning is no longer reported when the L-test contradicts it.
* The `rugnux` report gives the detector tilt, the measured tilt and the direct beam beside the beam centre, and a post-refined beam centre is judged against the run's own measurement rather than the file's.
* `--no-refine-tilt` holds the detector tilt at the value in the file, instead of zeroing it, when the calibration starts from the spots.
* The `jfjoch_viewer` grid scan view draws the cells in the proportion of the scan steps, so the map has the shape of the scanned area.

Reviewed-on: #76
Co-authored-by: Filip Leonarski <filip.leonarski@psi.ch>

tests/BeamCenterFromSpotsTest.cpp

@@ -282,3 +282,32 @@ TEST_CASE("BeamCenterFromSpots_SurvivesASpindleOffPerpendicular", "[BeamCenter]"
     CHECK(std::hypot(uncorrected->beam_x_pxl - truth.GetBeamX_pxl(),
                      uncorrected->beam_y_pxl - truth.GetBeamY_pxl()) > 3.0f * corrected_error);
 }
+
+// No detector is mounted exactly square to the beam, and a tilt separates the two centres this
+// estimator works with: the PONI it reports and the DIRECT BEAM both mirror lines are taken about.
+// The conversion between them is exact - it is where the vote is centred, where each tooth's
+// refinement starts, and how the answer is turned back out of the spindle frame - so a sign error
+// in it is a sign error of twice the offset in the answer. Here that offset is about 12 px, which
+// is 24 times the tolerance below.
+TEST_CASE("BeamCenterFromSpots_SurvivesADetectorTilt", "[BeamCenter]") {
+    DiffractionExperiment x = TestExperiment(Coord(1, 0, 0));
+    x.PoniRot1_rad(0.005f).PoniRot2_rad(-0.003f);
+    const DiffractionGeometry truth = OffsetBy(x.GetDiffractionGeometry(), 3.0f, -2.5f);
+    const Sweep sweep = MakeSweep(x, truth, PAIRS);
+
+    // The tilt has to be worth testing: with the two centres on top of each other the conversion
+    // is the identity and its sign is unobservable.
+    const auto [direct_x, direct_y] = truth.GetDirectBeam_pxl();
+    REQUIRE(std::hypot(direct_x - truth.GetBeamX_pxl(), direct_y - truth.GetBeamY_pxl()) > 5.0f);
+
+    SpindleEstimate fitted;
+    const auto estimate = FindBeamCenterFromSpotSymmetry(x, sweep.angle_deg, sweep.spots, &fitted);
+
+    REQUIRE(estimate.has_value());
+    CHECK(estimate->beam_x_pxl == Catch::Approx(truth.GetBeamX_pxl()).margin(0.5));
+    CHECK(estimate->beam_y_pxl == Catch::Approx(truth.GetBeamY_pxl()).margin(0.5));
+    CHECK(estimate->sigma_pxl < 1.0f);
+    // The spindle is perpendicular to the beam and on a lab axis here, so the tilt must not be
+    // read as an azimuth: what the fit sees of the detector belongs to the detector.
+    CHECK(fitted.azimuth_rad == Catch::Approx(0.0f).margin(5e-4));
+}