configurables must contain only settable properties

+ bug fix in TCLRequestHandler (decoding error)
+ cosmetic changes

Change-Id: I824e06f1acf975bb59c3312bb97fdfca23e6c975
Reviewed-on: https://forge.frm2.tum.de/review/c/sine2020/secop/playground/+/21826
Tested-by: JenkinsCodeReview <bjoern_pedersen@frm2.tum.de>
Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>

secop/protocol/interface/tcp.py

@@ -122,7 +122,8 @@ class TCPRequestHandler(socketserver.BaseRequestHandler):
                 try:
                     msg = decode_msg(origin)
                 except Exception as err:
-                    msg = origin.split(' ',3)
+                    # we have to decode 'origin' here. utf-8 and ascii may lead to encoding errors
+                    msg = origin.decode('latin-1').split(' ', 3)
                     result = (ERRORPREFIX + msg[0], msg[1], ['InternalError', str(err),
                                                              {'exception': formatException(),
                                                               'traceback': formatExtendedStack()}])