Unassign behavior tags by segments

There is currently no way to deselect behavior tags over a trajectory segment.

Proposal: Drag-and-drop a larva over a trajectory segment from a time step with no tag selected could be used to deselect all the tags assigned at each time step of the segment.

EDIT: Note that the UI logic is ready, with the active segment highlighted using the fallback color while dragging. On dropping, a log message says: Tag assignment cancelled (no tag to assign)