Change motion with /tp

Similar to how two more rotation arguments(I think that's the right word?) where added to /tp we could have 3 more motion arguments. They would function exactly like the position arguments with being able to use numbers for an exact value to set your motion , being able to use tildes for adding motion to your existing motion, and carets for adding motion in relative position. This would help to fill the gap in commands of not being able to modify player motion and would make certain things such as shootfacing easier with the benefit of not needing to add an entire new command for it.