Add velocity as a parameter in /summon

This would be very useful for a variety of things, such as testing alignments, or making cool displays. I think it could be implemented like this:
1. /summon <entityType: EntityType> [spawnpos: x y z] velocity [velocity: x y z]
2. /summon <entityType: EntityType> [spawnpos: x y z] vector [vector: yRot xRot velocity]
Example:
1. /summon allay ~~~ 10 3 5 - summons an Allay in current position with velocities x:10bpt,y:3bpt,z:5bpt
2. /summon tnt 50 101 70 80 45 10 - summons a TNT at 50,101,70 with a velocity vector of yRot:80, xRot:45, and vector size 10

(bpt: blocks per tick , xRot: rotation from x axis in degrees)