双向滑动，滑块可以重叠, 左边滑块不能移动到右边滑块的右边。Two slider can overlap, and the left slider can not be moved to right of the right slider
示例
增加了最小间隙
anonymity-du/DoubleSliderView-swift
双向滑动，滑块可以重叠, 左边滑块不能移动到右边滑块的右边。Two slider can overlap, and the left slider can not be moved to right of the right slider
SwiftMIT