ColorToVector.osl - fix parameter types

[geoffpedder]

The input and output types were opposite of what this conversion shader does, i flipped them around so the input is a color and the output is a vector

[johnhaddon]

Thanks @geoffpedder! Do you want this to go into a 1.3.x release, or is it OK in 1.4 (which is what main will become)?

I think we have a bit of additional work to do before we can merge this, since old files will have setValue( V3f() ) in them, and the new colour plugs won't accept that. Should be easy enough to add a conversion though - if you're interested I can point you in the right direction, or I can bash it out myself if you prefer.

[geoffpedder]

I think it's ok to wait until 1.4 as it still works as is. I had a feeling old scenes might be a problem. Maybe it's better if I let you handle that part. Thanks John!

[johnhaddon]

I had a feeling old scenes might be a problem. Maybe it's better if I let you handle that part.

I've dealt with that in #5653, which includes your original commit from this PR. Closing this one now in favour of that one...

[johnhaddon]

Thanks Geoff!