fix parameter inheritance

Correct inheritance has to follow the MRO, not only consider
the direct base classes.

Patchset 3: changed only tests, indicating that we need to change the code

Following patchsets include a major change in params.py and
modules.py. The parameter properties for inheritance, corresponding
mainly to the constructor arguments have to be stored separately
from the property values including inherited stuff.

Change-Id: Ibcbccb6abcc22e7e2d91df8f70ef64226684d8cc
Reviewed-on: https://forge.frm2.tum.de/review/c/sine2020/secop/playground/+/26805
Reviewed-by: Enrico Faulhaber <enrico.faulhaber@frm2.tum.de>
Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>
Tested-by: Jenkins Automated Tests <pedersen+jenkins@frm2.tum.de>

secop/proxy.py

@@ -182,7 +182,7 @@ def proxy_class(remote_class, name=None):
 
     for aname, aobj in rcls.accessibles.items():
         if isinstance(aobj, Parameter):
-            pobj = aobj.override(poll=False, handler=None, needscfg=False)
+            pobj = aobj.merge(dict(poll=False, handler=None, needscfg=False))
             attrs[aname] = pobj
 
             def rfunc(self, pname=aname):