improve handling of module init methods

- complain when super call is omitted (this is a common programming
  error in Mixins)
- redesign waiting mechanism for startup

+ rename MultiEvent method 'setfunc' to 'get_trigger'

Change-Id: Ica27a75597321f2571a604a7a55448cffb1bec5e
Reviewed-on: https://forge.frm2.tum.de/review/c/sine2020/secop/playground/+/27369
Tested-by: Jenkins Automated Tests <pedersen+jenkins@frm2.tum.de>
Reviewed-by: Enrico Faulhaber <enrico.faulhaber@frm2.tum.de>
Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>

secop_psi/trinamic.py

@@ -185,12 +185,12 @@ class Motor(PersistentMixin, HasIodev, Drivable):
             value = result * scale
         return value
 
-    def startModule(self, started_callback):
+    def startModule(self, start_events):
         # get encoder value from motor. at this stage self.encoder contains the persistent value
         encoder = self.get('encoder')
         encoder += self.zero
         self.fix_encoder(encoder)
-        super().startModule(started_callback)
+        super().startModule(start_events)
 
     def fix_encoder(self, encoder_from_hw):
         """fix encoder value