Fix shaders for all the objects

[islerfab]

Take dune.vert and dune.frag as example:

• Take headlight circle into account
• Add caustic effects
  • In vertex shader, define tex coord dimensions that make sense (just with x and z value of the model coordinate system)
• Add fog effects

[floruo]

all objects have a texture & fog

couldn't get caustics to work, even though it is included ...

[floruo]

caustics work, except for bottles & chest