Merge branch 'terencehill/slider_anim_improvements' into 'master'

Merge branch 'terencehill/slider_anim_improvements' into 'master'

Slider anim improvements

1. Fix sliders handle getting stuck in the initial position when dragging outside the handle

2. Make sliders animation work much better on quick repeated changes (e.g. with mouse wheel). Default animation is now easingQuadOut and lasts 0.5 s (instead of easingQuadInOut, 1 s), more similar to the list scrolling animation

3. Don't play any animation when loading the initial value of a slider since the animation can't be seen anyway (the menu takes 2-3 seconds to load); also the high number (200) of animations played at once on menu start caused a bug where slider's handles couldn't be moved for a while (up to 12 seconds with 30 fps)

Additional note about point 3: before the change of point 2 500+ animation were played at once on menu start, as 300+ animation updates counted as new animations!

See merge request !221