A few fixes to ALTUI displays

[rafale77]

1. Added slider to the Window Covering devices to represent and control open %
2. Make dimmable light sliders report current status instead of target which is of no significant use
3. Make RGB dimmable light display current color before target color. Particularly useful for plugins which do not use TargetColor variable (i.e ALTHUE)

[rafale77]

Hi Alexis,

The problem with doing it this way is when the dimmer is being actuated by other devices or manually. The vera in that case doesn't update it's target but only the status for devices with instant status capability. We would end up with a slider display being out of sync and representing nothing. I have also seen the flicker you speak of but it is only for a short period of time while the dimmer is moving to its target. Besides, the behavior I am proposing is also the same behavior observed by the vera UI as you would be able to see by entering the device screen. I would often see 2 different slider values for the in device slider and the dashboard slider.

[amg0]

directly manipulating the dimmer level without using the UPNP and the target logic is the mistake. I have experimented both mode and the way ALTUI does it ( show target and expect reconciliation later ) is the right way limiting flickering of UI in the majority of cases. I do not want to change this as it will create more problems that it fixes and that would be to work around a ill behavior of some other plugins/driver.
I am ok with the slider so if you submit a PR with just that, I can integrate it.

[rafale77]

Interesting. Is it due to openLuup not supporting UPnP then? Because I have not seen any use case where this slider behavior is correct with openLuup. It is also different from how ALTHUE and even the on/off switch indicator behaves it seems. It is purely cosmetic and is not changing any logical behavior so it isn't all that important. I will undo it but keep it in my fork since it's been reported to be misbehaving at least on openLuup.