Prevent colon confusion in output parsing

By use a magic string that shouldn't appear in code, we
make parsing easier.  Really we should use a parser or
something; but, this is an easy enough fix. 

Fixes mattijn#20

pycodestyle_magic.py

@@ -15,6 +15,7 @@
 import os
 import logging
 import copy
+import platform
 import pycodestyle as pycodestyle_module
 from flake8.api import legacy as flake8_module
 from contextlib import redirect_stdout
@@ -162,7 +163,8 @@ def pycodestyle(line, cell, auto=False):
         f.close()
     # now we can check the file by name.
     # we might be able to use 'stdin', have to check implementation
-    format = '%(row)d:%(col)d: %(code)s %(text)s'
+    format_divider = 'FORMAT_DIVIDER'
+    format = format_divider+'%(row)d'+format_divider'%(col)d'+format_divider+' %(code)s %(text)s'
     pycodestyle = pycodestyle_module.StyleGuide(format=format)
     # check the filename
     pcs_result = pycodestyle.check_files(paths=[f.name])
@@ -171,8 +173,7 @@ def pycodestyle(line, cell, auto=False):
 
     for line in stdout:
         #logger.info(line)     
-        # on windows drive path also contains :
-        line, col, error = line.split(':')[-4:] 
+        line, col, error = line.split(format_divider,3)[:1]
         # do not subtract 1 for line for %%pycodestyle, inc pre py3.6 string
         if auto:
             add = -1