[Feature Proposal]: Composite Trajectories

[kylelevy]

Hello,

Recently I was working on a project using the robotics-toolbox-python package and found there was no native support for combining trajectories. In my case, I found myself wanting to demo certain poses for a robot and so I created trajectories from each pose to the next and had to implement my own logic to concatenate the lists from both trajectories and add the last time value onto the second trajectory manually.

I think this is something that may be useful to others for constructing different trajectories and could potentially be implemented as the add method with checks for the final position / velocity matching the beginning of the second one.

I am happy to implement this if it is something that the maintainers think is worth while.

Let me know your thoughts :)