Additional composition output/export type: JSON

[Balthamos]

Hi! Loving your project, it's fantastic to see it constantly evolving!

I saw you mention elsewhere that you're not able to convert 2D JSON pose data to 3D, but what I'm wondering is if it would be possible to do the opposite:

When a pose is created and the camera has been positioned and the user clicks Generate, in addition to the skeletal .png/depth/normal/canny outputs, would it be possible to generate a 2D OpenPose JSON dictionary that represents the scene's current snapshot?

Similar to this:

{
  "people": [{
	"pose_keypoints_2d":
	[321,150,1,359,232,1,293,224,1,250,300,
	1,263,365,1,425,239,1,449,354,1,427,459,
	1,294,427,1,289,505,1,-1,-1,0,372,451,1,374,
	511,1,-1,-1,0,322,134,1,338,137,1,-1,-1,0,379,
	143,1]
	},{
	"pose_keypoints_2d":
	[173,157,1,137,231,1,72,230,1,46,319,1,118,337,
	1,202,231,1,216,322,1,199,346,1,123,414,1,99,
	501,1,-1,-1,0,190,410,1,195,507,1,-1,-1,0,159,142,
	1,177,145,1,125,149,1,-1,-1,0]
     }],
  "width": 512,
  "height": 512
}

It would be very useful as some tools can't import skeleton .pngs, but can import JSON.

Thanks!