Allow Tint slider to match Eyedropper range

When selecting a whitebalance point with the eyedropper, it can handily set values greater than +/-50 however as soon as you attempt to tweak the value, it snaps to 50.

I have to edit a LOT of really really badly lit stage photos, all the time, which feature horrific lighting schemes involving everyone's favourite Magenta LEDs.

Please just unlock the bounds on the slider so I can tweak the Tint point beyond 50. C1 already supports it or the WB dropper wouldn't function at these extremes, so it's just going to be an arbirary limiter in the UI slider.