Support for Dual Roller Shutter

[madzrobz]

Support for separately positioning the upper or lower curtain of dual roller shutters added.

[coveralls]

Coverage decreased (-0.3%) to 81.314% when pulling 5efe3c463903f3ec743e5052779b668737a628f2 on madzrobz:master into bb748d105723c1310236252376e13c4126d5597a on Julius2342:master.

[madzrobz]

The question remains, how to integrate with home assistant.

I still believe that simply adding a "curtain" parameter to the cover.set_position function would be sufficient and simpler then exposing three covers to home assistant (as discussed in 2019).

I did not explore whether/how KLF 200 reports position changes on the sub-covers. I'm not sure whether we would be able to maintain the correct position of these sub-covers in home assistant. Thus only providing a one-way function call to set the position of the sub-curtains seems to be perfectly fine for me.

[Julius2342]

Looks good to me. I think it is fine to add pylint-ignore for the too-many-branches and too-many-return statements warning.

And I would like to ask you to add a unit test :-)