Use open from io only for source loading

Merely replacing all the open() invocations caused issues with Python 2.

Fixes #241

Author: cyrus-and

.gdbinit

@@ -29,13 +29,13 @@ python
 # Imports ----------------------------------------------------------------------
 
 import ast
+import io
 import itertools
 import math
 import os
 import re
 import struct
 import traceback
-from io import open
 
 # Common attributes ------------------------------------------------------------
 
@@ -1185,7 +1185,7 @@ class Source(Dashboard.Module):
         if style_changed or file_name != self.file_name or ts and ts > self.ts:
             try:
                 # reload the source file if changed
-                with open(file_name, errors='ignore') as source_file:
+                with io.open(file_name, errors='ignore') as source_file:
                     highlighter = Beautifier(file_name, self.tab_size)
                     self.highlighted = highlighter.active
                     source = highlighter.process(source_file.read())