fix plot_input for usage with training batches

toolkit.py

@@ -1335,6 +1335,10 @@ class ClassificationProject(object):
                     break
                 if self.target_fields:
                     y = y[0]
+                try:
+                    x = self.get_input_flat(x)
+                except NameError:
+                    pass
                 bkg_batch = x[:,var_index][y==0]
                 sig_batch = x[:,var_index][y==1]
                 bkg_weights_batch = w[y==0]