add property to access label text and font
add property to access label text and font

- add property minLabelText, maxLabelText, minLabelFont, maxLabelFont
- add property leftHandleFrame, rightHandleFrame to get the handle position
Instamotor-Labs/TTRangeSlider,chengkaizone/TTRangeSlider,Instamotor-Labs/TTRangeSlider,fiantinangon/TTRangeSlider,mikeMTOL/TTRangeSlider,apaganobeleno/TTRangeSlider,WenryXu/TTRangeSlider,chengkaizone/TTRangeSlider,fiantinangon/TTRangeSlider,apaganobeleno/TTRangeSlider,fiantinangon/TTRangeSlider,protspace/TTRangeSlider,apaganobeleno/TTRangeSlider,tianfan/TTRangeSlider,Instamotor-Labs/TTRangeSlider,mikeMTOL/TTRangeSlider,WenryXu/TTRangeSlider,protspace/TTRangeSlider,WenryXu/TTRangeSlider,tianfan/TTRangeSlider,protspace/TTRangeSlider,chengkaizone/TTRangeSlider,TomThorpe/TTRangeSlider,mikeMTOL/TTRangeSlider,tianfan/TTRangeSlider