[Physics-2D] Algebra - Implement velocity2

[bal7hazar]

https://github.com/dimforge/nphysics/blob/master/src/algebra/velocity2.rs

[cpp-phoenix]

I can work on it @bal7hazar

[bal7hazar]

I think we miss some primitives, such as:

use na::{self, Isometry2, RealField, Rotation2, Vector, Vector1, Vector2, Vector3, U3};

So you will probably have to implement them in algebra crate, feel free to use orion if needed.

@ponderingdemocritus could you assign the issue please?

[cpp-phoenix]

Got it, Thanks @bal7hazar

[ScottyDavies]

Hi @bal7hazar Please can you assign this issue to me so I can start working on it immediately.