update to changes from mlz repo

- bug fixes in error.py
- add from * to raise statements
- fix py35 compatibility
- finalize omit_unchanged_within feature
- fix follwup bug (missing Param.override) in proxy.py

Change-Id: I621c01a0d5e1ec6696fb06f39666f3316fb53649

secop/errors.py

@@ -25,7 +25,7 @@
 class SECoPError(RuntimeError):
 
     def __init__(self, *args, **kwds):
-        RuntimeError.__init__(self)
+        super().__init__()
         self.args = args
         for k, v in list(kwds.items()):
             setattr(self, k, v)
@@ -151,7 +151,8 @@ EXCEPTIONS = dict(
     IsError=IsErrorError,
     Disabled=DisabledError,
     SyntaxError=ProtocolError,
-    NotImplementedError=NotImplementedError,
+    NotImplemented=NotImplementedError,
+    ProtocolError=ProtocolError,
     InternalError=InternalError,
     # internal short versions (candidates for spec)
     Protocol=ProtocolError,