Fixes #1564

[PeterRobots]

Fixes Moved the brightness helper check on scroll to above any scroll value changes.

[PeterRobots]

After testing I still need to fix the brightness jumping, but scroll jumping is fixed.

[PeterRobots]

After testing I still need to fix the brightness jumping, but scroll jumping is fixed.

Fixed with Commit: 5a4d1dc

• scroll brightness calculation to just use *100/MIN
• First activation of scroll brightness just posts current value
• action_down now sets currentPercent to actual current brightness percentage using updateCurrentValue()

Scroll brightness and scroll mode are now much more independent. Brightness no longer jumps values on successive uses or scrolling pages.