decompose for Cylinder3 returns faces with back facing orientation convention

[TsurHerman]

This can be seen when rendering in GLVisualize

code:

using GLVisualize,GeometryTypes,ColorTypes
window = glscreen()
C = Cylinder3{Float32}([-1,-1,-1],[1,1,1],1)
_view(visualize(GLNormalMesh(C,100),color = RGBA{Float32}(1,0,0,1)))
renderloop(window)

the inside is brighter than the outside

[SimonDanisch]

fixed by #110