Enhanced Trajectories

The 2.0 trajectories were purposefully left very bare, in order to leave space for future extension into the trajectories we actually need. This issue serves as a collector for relevant sub-issues, as well as any design principles and goals and their discussions.

Specifically, the design of trajectories should support the building up of trajectories out of multiple primitives, including e.g. clothoids, splines, and others in a unified way. This should also enable incremental build up of trajectories, by e.g. combining trajectories with specific rules of how to ensure proper levels of smoothness.

The design of trajectories shall be as broad as necessary to enable their use across all places in the language that need to address trajectory-like information, including e.g. use in overtake or lane change maneuvers, as well as purely following a given trajectory.

The design shall take into account both actual trajectories, including both locating and timing information, as well as pure paths that lack timing information in a unified way, e.g. allowing reuse of a full trajectory as a pure path when needed, or combining a path with orthogonal timing information (e.g. speed profile) to then form a fully defined trajectory.

Relevant issues of note, also including 1.x compatibility are linked to this issue.