Fixed typo and made a line more PEP-8

umbra/controller.py

 from filereader import CSVReader
-from filereader import CSVWriter
+from filereader import CSVWriter, TxtWriter
 from utils import Utils as ut
 import os
 import numpy as np
@@ -28,7 +28,7 @@ class Controller:
         return self._source_files
 
     @source_files.setter
-    def shadow_files(self, val):
+    def source_files(self, val):
         self._source_files = val
 
     @property
@@ -121,9 +121,11 @@ class Controller:
                     files.remove(s)
                 self._view.button_status("select {}".format(type), "normal")
             else:
-                selection = [file for file in files if selection.lower() in file.lower()][0]
+                selection = [file for file in files if selection.lower() in
+                             file.lower()][0]
                 files.remove(selection)
-                self._view.button_status("select_folder {}".format(type), "normal")
+                self._view.button_status("select_folder {}".format(type),
+                                         "normal")
             self._view.update_files(files, type)
 
     def _compare_files(self):