introduced StringIO

introduce line oriented communication
+ HasIodev Mixin
+ minor fixes
Change-Id: I22605824d2f45147224840172bae281f85c80a11
Reviewed-on: https://forge.frm2.tum.de/review/c/sine2020/secop/playground/+/21953
Tested-by: JenkinsCodeReview <bjoern_pedersen@frm2.tum.de>
Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>

secop/protocol/interface/tcp.py

@@ -124,7 +124,7 @@ class TCPRequestHandler(socketserver.BaseRequestHandler):
                 except Exception as err:
                     # we have to decode 'origin' here
                     # use latin-1, as utf-8 or ascii may lead to encoding errors
-                    msg = origin.decode('latin-1').split(' ', 3) + (None,) # make sure len(msg) > 1
+                    msg = origin.decode('latin-1').split(' ', 3) + [None] # make sure len(msg) > 1
                     result = (ERRORPREFIX + msg[0], msg[1], ['InternalError', str(err),
                                                              {'exception': formatException(),
                                                               'traceback': formatExtendedStack()}])