Remove replanning

[mjansen4857]

Replanning seems to be misused more often than it is actually helpful, so it should probably just be removed to the point of only re-generating a trajectory if the robot does not match the path's ideal starting state.

The current implementation adds a lot of potential footguns for the ability to join a path anywhere, which really isn't something the user should be wanting to do anyways. Any more complex on-the-fly path planning should be left up to the user instead of creating a general solution that doesn't work that great.