Unified Tag, Marker and Detection API

[oscarlorentzon]

Define the structure for a unified API for putting 2D and 3D objects in the viewer.

• Tag component
• Marker component
• Detection component

[oscarlorentzon]

#78 and #79 are related to this issue.

[oscarlorentzon]

General API structure agreed upon:

new Tag(id, geometry, options)
new Marker(id, latLonAlt, options)
new Detection(id, geometry, options)

Implementation details should be handled in separate issues.