config option to invert signal that is send for shutters

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A couple of weeks ago i created this pull request: https://github.com/pimatic/pimatic-homeduino/pull/71

Since then i got no reaction.

@mwittig or @sweetpi: Do you think this PR could be merged? There are other PRs that haven’t been touched, too.

@michbeck100 Honestly, I don’t see the need for this PR, but I have no experience with shutters. So, I leave this to @sweetpi to decide. Maybe shutter users can also comment on this.

@mwittig I can explain, why this can be pretty important for some shutter users: If the RF receiver is trained with the wrong buttons (using off instead of on button) and then put inside the wall, its not easy to get it out again, to train it again. And pimatic will raise the shutter when the user presses the button to lower it and vice versa. With this change its easy to fix this behavior without training the receiver again.

But why should yout train yor receiver with the wrong buttons?
I thinks its more confusing because on the remote its still wrong.

@Flop2006 You can use a standard remote like http://intertechno.at/front/produkte/sender/handsender/its-150/ which has just on/off buttons to train the receiver. Now tell me whats the button to open the window? On or off? I think that’s not obvious.

Ok, I see, the “wrong” remote is the problem. That makes it much clearer.

@michbeck100 I’ll ask @sweetpi to review

its not only to train the device with the wrong buttons. if you accidentially mess up with the motor wiring then the up wire will get the down signal and vice versa. having a beamer screen where i have this issue. screwed everything together, stored it in a wall box and this is located behind a heavy and big shelf. well, now i really don’t want to disassemble the shelf again. used a workaround with a dummy shutter in the meantime