Repalce codecs.open with open

Since Python 3, using codecs.open() as the builtin supports an encoding
argument. Use the simpler and more conventional pattern.

codespell_lib/_codespell.py

@@ -18,7 +18,6 @@
 """
 
 import argparse
-import codecs
 import configparser
 import fnmatch
 import os
@@ -175,7 +174,7 @@ def open(self, filename):
 
     def open_with_chardet(self, filename):
         self.encdetector.reset()
-        with codecs.open(filename, 'rb') as f:
+        with open(filename, 'rb') as f:
             for line in f:
                 self.encdetector.feed(line)
                 if self.encdetector.done:
@@ -184,7 +183,7 @@ def open_with_chardet(self, filename):
         encoding = self.encdetector.result['encoding']
 
         try:
-            f = codecs.open(filename, 'r', encoding=encoding)
+            f = open(filename, encoding=encoding)
         except UnicodeDecodeError:
             print("ERROR: Could not detect encoding: %s" % filename,
                   file=sys.stderr)
@@ -203,7 +202,7 @@ def open_with_internal(self, filename):
         curr = 0
         while True:
             try:
-                f = codecs.open(filename, 'r', encoding=encodings[curr])
+                f = open(filename, encoding=encodings[curr])
             except UnicodeDecodeError:
                 if not self.quiet_level & QuietLevels.ENCODING:
                     print("WARNING: Decoding file using encoding=%s failed: %s"
@@ -439,19 +438,19 @@ def parse_ignore_words_option(ignore_words_option):
 
 
 def build_exclude_hashes(filename, exclude_lines):
-    with codecs.open(filename, 'r') as f:
+    with open(filename) as f:
         for line in f:
             exclude_lines.add(line)
 
 
 def build_ignore_words(filename, ignore_words):
-    with codecs.open(filename, mode='r', encoding='utf-8') as f:
+    with open(filename, encoding='utf-8') as f:
         for line in f:
             ignore_words.add(line.strip())
 
 
 def build_dict(filename, misspellings, ignore_words):
-    with codecs.open(filename, mode='r', encoding='utf-8') as f:
+    with open(filename, encoding='utf-8') as f:
         for line in f:
             [key, data] = line.split('->')
             # TODO for now, convert both to lower. Someday we can maybe add
@@ -737,7 +736,7 @@ def parse_file(filename, colors, summary, misspellings, exclude_lines,
                 print("%sFIXED:%s %s"
                       % (colors.FWORD, colors.DISABLE, filename),
                       file=sys.stderr)
-            with codecs.open(filename, 'w', encoding=encoding) as f:
+            with open(filename, 'w', encoding=encoding) as f:
                 f.writelines(lines)
     return bad_count