Maya: Account and ignore free image planes.

[tokejepsen]

Changelog Description

Free image planes do not have the -> path separator, so we need to account for that.

Testing notes:

1. Create camera in Maya.
2. Create free image plane.
3. Assign camera to image plane.
4. Publish.

[BigRoy]

Funny - I just fixed this today.. and more!

It also captures images planes that aren't actually connected currently (e.g. those that are set to "see through camera" or whatever but aren't input connections anymore - so I fixed that up as well by explicitly only looking for image planes that are connected as inputs to the imagePlane attribute.

My code is here

[tokejepsen]

@BigRoy if you setup a PR, I think dont mind closing this one.

[moonyuet]

Code looks good for me. Tested in AYON. Looks good.

loaded by referencing the ma file. Works fine.

[kalisp]

Applied changes from BigRoy.

[LiborBatek]

I did create free imagePlane and defined a camera1 as a looking through camera

Not sure what does mean step 3 exactly assign a camera to imagePlane in testing steps tho...

Publish went without any issues and fine. Again quite vague what to publish (Camera??)

However as we strip everything during camera product publish not sure whats the point here?

@BigRoy @tokejepsen Should I somehow connect the imagePlane then (node editor??)

Also only matchMove and mayaScene product can publish Camera with imagePlanes no?