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_ess/epics.py

@@ -181,7 +181,7 @@ class EpicsDrivable(Drivable):
             return Drivable.Status.UNKNOWN, self._read_pv(self.status_pv)
         # status_pv is unset, derive status from equality of value + target
         if self.read_value() == self.read_target():
-            return (Drivable.Status.OK, '')
+            return (Drivable.Status.IDLE, '')
         return (Drivable.Status.BUSY, 'Moving')
 
 
@@ -221,7 +221,7 @@ class EpicsTempCtrl(EpicsDrivable):
         at_target = abs(self.read_value(maxage) - self.read_target(maxage)) \
             <= self.tolerance
         if at_target:
-            return (Drivable.Status.OK, 'at Target')
+            return (Drivable.Status.IDLE, 'at Target')
         return (Drivable.Status.BUSY, 'Moving')
 
     # TODO: add support for strings over epics pv