CXR file format as an option for render queue output

From forum post at https://forum.corona-renderer.com/index.php?topic=42720.0

"Currently c4d users are able to save out exr files when using the render queue, however cxr isn't an option. i feel like we are missing out on a powerful option with regards to the corona image editor being able to use lightmix with these types of files.

Although we can save cxr's for this use from the vfb, when queueing and rendering multiple images each evening this isn't an option."

As a note from the Corona team, this would require the re-writing of export / save routines ourselves rather than relying on the pre-made Cinema 4D save routines (where we can't control what file formats they choose to offer).