Use tokenize.open for run_checks and add note to TODO

doc/TODO

@@ -55,6 +55,8 @@ Downloads
 Improvements / minor features
 =============================
 
+- Use tokenize.open where appropriate.
+- Add pylint checker to warn on open() without encoding.
 - We should have something like utils.debug.qenum_key for QFlags.
 - Honour icognito mode for cookies etc.
 - Make sure commands in config are _complete_

scripts/run_checks.py

@@ -36,6 +36,7 @@ import os
 import os.path
 import unittest
 import logging
+import tokenize
 from collections import OrderedDict
 
 try:
@@ -186,7 +187,7 @@ def check_vcs_conflict(target):
         for (dirpath, _dirnames, filenames) in os.walk(target):
             for name in (e for e in filenames if e.endswith('.py')):
                 fn = os.path.join(dirpath, name)
-                with open(fn, 'r') as f:
+                with tokenize.open(fn) as f:
                     for line in f:
                         if any(line.startswith(c * 7) for c in '<>=|'):
                             print("Found conflict marker in {}".format(fn))