Support camera poses

[slimbuck]

Fixes: #186

ss-camera-poses.mov

This PR includes the following changes:

• add the ability to load colmap cameras.json format camera poses
• displays the list of poses in a list on the view options panel
  • the list will likely be moved to its own popup window
• supports switching between camera poses and playing back the poses as an animation
• update input handling for popup windowsb
• update npm dependencies except eslint
• fix spotty grid rendering

[willeastcott]

Cool. But I still strongly feel that this should be its own panel.