fix(Math): Add hex2float function
fix(Math): Add hex2float function

That function allow to convert web color format (i.e. #aaa, #ffdd10, aaa, 40fd3a, #aabbcc00) to
floating point representation of RGB or RGBA when alpha provided

Kitware/vtk-js,Kitware/vtk-js,Kitware/vtk-js,Kitware/vtk-js