improve mercury temperature loop

- remove appearance of Done
- add auto flow
- try up to 3 times in 'change' method if read back does not match

Change-Id: I98928307bda87190d34aed663023b157311d4495
Reviewed-on: https://forge.frm2.tum.de/review/c/secop/frappy/+/30981
Tested-by: Jenkins Automated Tests <pedersen+jenkins@frm2.tum.de>
Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>

.pylintrc

@@ -218,7 +218,7 @@ max-branches=50
 max-statements=150
 
 # Maximum number of parents for a class (see R0901).
-max-parents=25
+max-parents=20
 
 # Maximum number of attributes for a class (see R0902).
 max-attributes=50