omit updates of unchanged values within short time

Sometimes it happens, that the same value determined once is
assigned several times to a parameter within a very short period.
Sending multiple updates is not useful in this case.

Change-Id: Icea66934c831fd9b2eac7d0394a124d002469914
Reviewed-on: https://forge.frm2.tum.de/review/c/sine2020/secop/playground/+/27091
Tested-by: Jenkins Automated Tests <pedersen+jenkins@frm2.tum.de>
Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>

secop/protocol/dispatcher.py

@@ -60,10 +60,11 @@ def make_update(modulename, pobj):
 
 
 class Dispatcher:
-
     def __init__(self, name, logger, options, srv):
         # to avoid errors, we want to eat all options here
         self.equipment_id = options.pop('id', name)
+        # time interval for omitting updates of unchanged values
+        self.omit_unchanged_within = options.pop('omit_unchanged_within', 0.1)
         self.nodeprops = {}
         for k in list(options):
             self.nodeprops[k] = options.pop(k)