try to follow PEP8

- fixed most important code after checking with flake8
- ignored code which has to be reworked or removed
+ mark unused code with 'TODO: remove ...'

Change-Id: Ic45e541049e391e2853d29cd64bb0963bd9a2125
Reviewed-on: https://forge.frm2.tum.de/review/c/sine2020/secop/playground/+/25053
Tested-by: Jenkins Automated Tests <pedersen+jenkins@frm2.tum.de>
Reviewed-by: Enrico Faulhaber <enrico.faulhaber@frm2.tum.de>

secop/client/__init__.py

@@ -31,7 +31,7 @@ from threading import Event, RLock, current_thread
 import secop.errors
 import secop.params
 from secop.datatypes import get_datatype
-from secop.lib import formatExtendedStack, formatExtendedTraceback, mkthread
+from secop.lib import mkthread
 from secop.lib.asynconn import AsynConn, ConnectionClosed
 from secop.protocol.interface import decode_msg, encode_msg_frame
 from secop.protocol.messages import COMMANDREQUEST, \
@@ -161,7 +161,6 @@ class ProxyClient:
             if not cblist:
                 self.callbacks[cbname].pop(key)
 
-
     def callback(self, key, cbname, *args):
         """perform callbacks