Complete removal of six compatibility library

This completes the migration started in PR #47 by removing all remaining
references to the six library and replacing them with native Python 3
standard library imports.

Changes:
- Replace six.moves.BaseHTTPServer with http.server
- Replace six.moves.socketserver with socketserver
- Remove six from setup.py install_requires

Files modified:
- pywebdav/lib/utils.py: Import BaseHTTPRequestHandler from http.server
- pywebdav/server/server.py: Import HTTPServer and ThreadingMixIn from stdlib
- pywebdav/lib/AuthServer.py: Replace all six.moves.BaseHTTPServer references
- setup.py: Remove six dependency

All imports verified to work correctly with Python 3.

Author: claude

pywebdav/lib/AuthServer.py

@@ -6,7 +6,7 @@
 
 import base64
 import binascii
-import six.moves.BaseHTTPServer
+from http.server import BaseHTTPRequestHandler
 
 
 DEFAULT_AUTH_ERROR_MESSAGE = """
@@ -28,7 +28,7 @@ def _quote_html(html):
     return html.replace("&", "&amp;").replace("<", "&lt;").replace(">", "&gt;")
 
 
-class AuthRequestHandler(six.moves.BaseHTTPServer.BaseHTTPRequestHandler):
+class AuthRequestHandler(BaseHTTPRequestHandler):
     """
     Simple handler that can check for auth headers
 
@@ -41,7 +41,7 @@ class AuthRequestHandler(six.moves.BaseHTTPServer.BaseHTTPRequestHandler):
     DO_AUTH = 1
 
     def parse_request(self):
-        if not six.moves.BaseHTTPServer.BaseHTTPRequestHandler.parse_request(self):
+        if not BaseHTTPRequestHandler.parse_request(self):
             return False
 
         if self.DO_AUTH:

pywebdav/lib/utils.py

@@ -6,7 +6,7 @@
 import urllib.parse
 
 from .constants import RT_ALLPROP, RT_PROPNAME, RT_PROP
-from six.moves.BaseHTTPServer import BaseHTTPRequestHandler
+from http.server import BaseHTTPRequestHandler
 
 def gen_estring(ecode):
     """ generate an error string from the given code """

pywebdav/server/server.py

@@ -13,8 +13,8 @@
 logging.basicConfig(level=logging.WARNING)
 log = logging.getLogger('pywebdav')
 
-from six.moves.BaseHTTPServer import HTTPServer
-from six.moves.socketserver import ThreadingMixIn
+from http.server import HTTPServer
+from socketserver import ThreadingMixIn
 
 try:
     import pywebdav.lib

setup.py

@@ -46,6 +46,6 @@
     entry_points={
       'console_scripts': ['davserver = pywebdav.server.server:run']
       },
-    install_requires = ['six'],
+    install_requires = [],
     setup_requires=['git-versioner'],
     )