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>

test/test_multievent.py

@@ -26,8 +26,8 @@ from secop.lib.multievent import MultiEvent
 
 def test_without_timeout():
     m = MultiEvent()
-    s1 = m.setfunc(name='s1')
-    s2 = m.setfunc(name='s2')
+    s1 = m.get_trigger(name='s1')
+    s2 = m.get_trigger(name='s2')
     assert not m.wait(0)
     assert m.deadline() is None
     assert m.waiting_for() == {'s1', 's2'}
@@ -45,10 +45,10 @@ def test_with_timeout(monkeypatch):
     m = MultiEvent()
     assert m.deadline() == 0
     m.name = 's1'
-    s1 = m.setfunc(10)
+    s1 = m.get_trigger(10)
     assert m.deadline() == 1010
     m.name = 's2'
-    s2 = m.setfunc(20)
+    s2 = m.get_trigger(20)
     assert m.deadline() == 1020
     current_time += 21
     assert not m.wait(0)