2D vector library

Create and use 2D vectors.

Example

```rust use vector2::Vector2;

// Create a Vector2 let vector2 = Vector2::new(1.0, 0.5);

// (1.0, 0.0) let other = Vector2::RIGHT;

// Add two Vector2s let added = vector2 + other;

asserteq!(added.x, 2.0); asserteq!(added.y, 0.5); ```