Added planetary shading images & img subfolders and modified TODO
Each planet image by Liana has been subjected to 24 angles of light
producing the 3D planetary images complete with proper shading.

Planets completed:
1. Aquatic
2. Arctic
3. Desert
4. Gaseous
5. OreRich
6. Tropical

I also reorganized the img folder to accomodate large volumes of required images.