Support image texture for channel uniforms

[Makio64]

Use PIL to load the image. Tested with png/jpg. The noise by default is remove.

[alexjc]

Awesome PR! Couple of things:

• Can you make this PR again with mostly unchanged whitespace (instead of converting to tabs). It's hard to read the diff this way.
• Also, if you make the default None then you can use noise when no file has been specified.

Thanks!

[Makio64]

Ok, I'll do that tomorrow 👍

[JuusoKaari]

Works like a charm! Very nice work.
But, it also made me wonder, would it be possible to load image sequences / videos too through PIL?

[Makio64]

@JuusoKaari : yes possible, I guess the best should be to use openCV to transform the frame of the video you want to image, and each frame you seek the video to the correct time and redo it.