tracking for 360° video / equirectangular footage

as 360-cameras become more common, more footage is created and it is more often consumed as a 360-video in a vr headset.

as such, vfx and 3d objects need to be added to these videos.

support for 360degree video tracking would require:

• ability for the tracker to "wrap around" once a track moves out of the image
• solver for 360° camera projections (equirectangular, or others)
• additional options in the ui

assuming a uniform equirectangular projection, the tracker math should be a bit simpler than lens projection