Make sure the composite texture is reloaded.
Add missing binding.
Fix incorrect texture unit calculation.

The base layer is included in the mLayers collection.
Set the skirt size to 1 meter.

With the endless world there should be no visible skirts at all.
Add support for multipass terrain rendering.
Fix fog in multipass.

Only apply full fog in the last pass when doing multi pass. Else the fog
will stack up with each pass.