[Bf-python] some missing things from the api

[Campbell Barton]

Hi, there are 2 missing functions in the Python API

1) Texture accsess in world data
2) it is impossible to render an image and save it to a name you want.
...render is only possible with renderAnim which adds numbers  to the image.
...the only solution is to render the animation as 1 frame and then 
rename it
(requiring the os module, and sombody to have a python install), 
impracticle fopr such a simple feature.

# This renames a newly rendered file, requires the os module.
    os.rename( sys.expandpath(outfile+'#'), outfile )

- Cam