various small fixes

- fix some earlyInit and initModules methods
- remove some comments
- change name of Done unique value to 'Done', this seems more
  useful for __repr__ and debug logging

Change-Id: I73f0e09bfef858ddca11bba0e92e941ebc151160
Reviewed-on: https://forge.frm2.tum.de/review/c/sine2020/secop/playground/+/27907
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/ppms.py

@@ -168,7 +168,7 @@ class Channel(PpmsBase):
                   datatype=IntRange(1, 4), export=False)
 
     def earlyInit(self):
-        Readable.earlyInit(self)
+        super().earlyInit()
         if not self.channel:
             self.channel = self.name