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/protocol/interface/__init__.py

@@ -25,6 +25,7 @@ import json
 
 EOL = b'\n'
 
+
 def encode_msg_frame(action, specifier=None, data=None):
     """ encode a msg_triple into an msg_frame, ready to be sent