Add streak masking

Also add the STREAK mask plane to the test exposure util.
Without this, the pixelFlags plugin will fail, and we
cannot run maskStreaksTask directly since it's in pipe_tasks.

python/lsst/ip/diffim/detectAndMeasure.py

@@ -168,6 +168,10 @@ def setDefaults(self):
         self.forcedMeasurement.slots.centroid = "base_TransformedCentroid"
         self.forcedMeasurement.slots.shape = None
 
+        # Keep track of which footprints contain streaks
+        self.measurement.plugins['base_PixelFlags'].masksFpAnywhere = ['STREAK']
+        self.measurement.plugins['base_PixelFlags'].masksFpCenter = ['STREAK']
+
 
 class DetectAndMeasureTask(lsst.pipe.base.PipelineTask):
     """Detect and measure sources on a difference image.

python/lsst/ip/diffim/utils.py

@@ -1265,6 +1265,7 @@ def detectTestSources(exposure):
         sigma=None,  # The appropriate sigma is calculated from the PSF
         doSmooth=True
     )
+    exposure.mask.addMaskPlane("STREAK")  # Cannot run maskStreaksTask here, as it's in pipe_tasks
     selectSources = detRet.sources
     selectMeasurement.run(measCat=selectSources, exposure=exposure)