merge 'parameters' and 'commands' to 'accessibles'

- for now, the definition also accepts the old syntax
  (to be changed later)
- Commands have datatype CommandType
- do not need keyword for the decription parameter of Override
- issue a Warning when a Parameter is overwritten without Overrride
  (this should be turned into an error message)
-

Change-Id: Ib2c0f520abb5b4d7e6aed4d77a0d2b8bc470a85a
Reviewed-on: https://forge.frm2.tum.de/review/18251
Tested-by: JenkinsCodeReview <bjoern_pedersen@frm2.tum.de>
Reviewed-by: Enrico Faulhaber <enrico.faulhaber@frm2.tum.de>
Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>

secop/gui/nodectrl.py

@@ -194,7 +194,7 @@ class ReadableWidget(QWidget):
 
         # XXX: avoid a nasty race condition, mainly biting on M$
         for i in range(15):
-            if 'status' in self._node.describing_data['modules'][module]['parameters']:
+            if 'status' in self._node.describing_data['modules'][module]['accessibles']:
                 break
             sleep(0.01*i)
 
@@ -246,7 +246,7 @@ class ReadableWidget(QWidget):
         # XXX: also connect update_status signal to LineEdit ??
 
     def update_status(self, status, qualifiers=None):
-        display_string = self._status_type.subtypes[0].entries.get(status[0])
+        display_string = self._status_type.subtypes[0]._enum[status[0]].name
         if status[1]:
             display_string += ':' + status[1]
         self.statusLineEdit.setText(display_string)