make datatypes immutable

in order to prevent modifying parameters without automatically
trigger updates, all datatypes must be immutable.

TupleOf and ArrayOf: change from list to tuple
StructOf: use ImmutableDict

most existing code should work properly, the only thing to consider are
equality comparisons with lists, which will result to False all the time

the changes in secop_psi/ppms.py (using tuples instead of lists for status values)
are not really necessary, but lead to less confusing code

Change-Id: I181f412b5cd55af296b2e5120af82449beb03f54
Reviewed-on: https://forge.frm2.tum.de/review/c/sine2020/secop/playground/+/22972
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>

test/test_modules.py

@@ -156,7 +156,7 @@ def test_ModuleMeta():
 
     # check for inital updates working properly
     o1 = Newclass1('o1', logger, {'.description':''}, srv)
-    expectedBeforeStart = {'target': 0.0, 'status': [Drivable.Status.IDLE, ''],
+    expectedBeforeStart = {'target': 0.0, 'status': (Drivable.Status.IDLE, ''),
             'param1': False, 'param2': 1.0, 'a1': 0.0, 'a2': True, 'pollinterval': 5.0,
             'value': 'first'}
     assert updates.pop('o1') == expectedBeforeStart
@@ -165,7 +165,7 @@ def test_ModuleMeta():
     o1.startModule(event.set)
     event.wait()
     # should contain polled values
-    expectedAfterStart = {'status': [Drivable.Status.IDLE, ''],
+    expectedAfterStart = {'status': (Drivable.Status.IDLE, ''),
             'value': 'second'}
     assert updates.pop('o1') == expectedAfterStart