Initial Qt5/Python3 switch

This converts the GUI code to use Qt5 and Python3

The GUI is still somewhat buggy, and it can't open files yet,
but seems to be mostly working, extensive testing will
be needed before this can be released.

relational/maintenance.py

@@ -19,9 +19,10 @@
 #
 # Stuff non-related to relational algebra, but used for maintenance.
 
-import httplib
-import urllib
-import relation
+import http.client
+import urllib.parse
+
+from relational import relation
 
 
 def send_survey(data):
@@ -33,10 +34,10 @@ def send_survey(data):
         post += '%s: %s\n' % (i, data[i])
 
     # sends the string
-    params = urllib.urlencode({'survey': post})
+    params = urllib.parse.urlencode({'survey': post})
     headers = {"Content-type":
                "application/x-www-form-urlencoded", "Accept": "text/plain"}
-    connection = httplib.HTTPConnection('feedback-ltworf.appspot.com')
+    connection = http.client.HTTPConnection('feedback-ltworf.appspot.com')
     connection.request("POST", "/feedback/relational", params, headers)
 
     return connection.getresponse()
@@ -46,7 +47,7 @@ def check_latest_version():
     '''Returns the latest version available.
     Heavely dependent on server and server configurations
     not granted to work forever.'''
-    connection = httplib.HTTPConnection('feedback-ltworf.appspot.com')
+    connection = http.client.HTTPConnection('feedback-ltworf.appspot.com')
     connection.request("GET", "/version/relational")
     r = connection.getresponse()
 
@@ -54,7 +55,7 @@ def check_latest_version():
     s = r.read()
     if len(s) == 0:
         return None
-    return s.strip()
+    return str(s.strip())
 
 
 class interface (object):