treat specifier of describe message

for debugging purposes, getting the description of a module
or even a parameter is usefull

therefore the following will work

describe <module>
describe <module>:<param>

Change-Id: Ie262ae12c23d1c151cdc01830ad4f8fd5ec3c5f1
Reviewed-on: https://forge.frm2.tum.de/review/c/sine2020/secop/playground/+/25962
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/params.py

@@ -187,7 +187,6 @@ class Parameter(Accessible):
         self._constant = constant
 
     def __get__(self, instance, owner):
-        # not used yet
         if instance is None:
             return self
         return instance.parameters[self.name].value