Format files with black

- Format all files with black
- Update tox.ini flake8 arguments to be compatible
- Add black to requirements-extra.txt
- Reduce ignored flake8 rules and fix a few violations

core/gui/problem_dialog.py

@@ -1,29 +1,29 @@
 # Created By: Virgil Dupras
 # Created On: 2010-04-12
 # Copyright 2015 Hardcoded Software (http://www.hardcoded.net)
-# 
-# This software is licensed under the "GPLv3" License as described in the "LICENSE" file, 
-# which should be included with this package. The terms are also available at 
+#
+# This software is licensed under the "GPLv3" License as described in the "LICENSE" file,
+# which should be included with this package. The terms are also available at
 # http://www.gnu.org/licenses/gpl-3.0.html
 
 from hscommon import desktop
 
 from .problem_table import ProblemTable
 
+
 class ProblemDialog:
     def __init__(self, app):
         self.app = app
         self._selected_dupe = None
         self.problem_table = ProblemTable(self)
-    
+
     def refresh(self):
         self._selected_dupe = None
         self.problem_table.refresh()
-    
+
     def reveal_selected_dupe(self):
         if self._selected_dupe is not None:
             desktop.reveal_path(self._selected_dupe.path)
-    
+
     def select_dupe(self, dupe):
         self._selected_dupe = dupe
-