[Bf-docboard] New Lighting chapter

[mindrones]

Hi Bastien,

we already talked in IRC, seems like it's best to let the TOC mimick the URLs structure, so after some clenup here's my proposal (same for URLs structure and TOC):

Lighting

  *Lights* (intro from your "Common Options")
    Light properties (splitting Meta:Sandbox/Lighting/Lamps/Common Options)
    Light Attenuation
    Textures (splitting Meta:Sandbox/Lighting/Lamps/Common Options)
    What light affects (splitting Meta:Sandbox/Lighting/Lamps/Common Options)
    Lights in other contexts    (is "Related settings" now)

  *Shadows* (now it is in "Meta:Sandbox/Lighting/Light and Shadows")
  *Volumetric lights* (now it is in "Meta:Sandbox/Lighting/Light and Shadows")

  *Lamps*
    Lamp
      Raytraced Shadows
    Hemi
    Area
      Raytraced Shadows
    Spot
      Buf Shadows
      Buffered Halo
      Raytraced Halo
    Sun
      Raytraced Shadows
      Sky and Atmosphere
    Lighting Rigs

  *Scene light*
    Ambient Light
    Ambient Occlusion
    Exposure

You already agreed to this, let see what others think about this :)

Regards,
Luca