Remove unpolarized probe from SA plot (#151)

When Polarized and Unpolarized probes exist, Unpolarized probe is plotted in "SA" views as default view (log scale) such that the SA for polarized probes cannot be viewed. Removes this from the plot.

refl1d/probe.py

@@ -578,7 +578,7 @@ def oversample(self, n=20, seed=1):
         Note: :meth:`oversample` will remove the extra Q calculation
         points introduced by :meth:`critical_edge`.
         """
-        
+
         rng = numpy.random.RandomState(seed=seed)
         T = rng.normal(self.T[:, None], self.dT[:, None], size=(len(self.dT), n-1))
         L = rng.normal(self.L[:, None], self.dL[:, None], size=(len(self.dL), n-1))
@@ -743,8 +743,8 @@ def plot(self, view=None, **kwargs):
             self.plot_residuals(**kwargs)
         elif view == 'fft':
             self.plot_fft(**kwargs)
-        elif view == 'SA': # SA uses default plot
-            self.plot(view=None, **kwargs)
+        elif view == 'SA': # SA does not plot since it does not exist
+            pass
         else:
             raise TypeError("incorrect reflectivity view '%s'"%view)
 
@@ -1767,7 +1767,7 @@ def _calculate_union(self):
                 self._set_calc(self.T, self.L)
             else:
                 self._oversample(self.oversampling, self.oversampling_seed)
-            
+
             self._theta_offsets = theta_offsets
 
     @property