good physics based movement
private Rigidbody rb;
void Start ()
{
	rb = GetComponent<Rigidbody>();
}
void FixedUpdate ()
{
	float moveHorizontal = Input.GetAxis ("Horizontal");
	float moveVertical = Input.GetAxis ("Vertical");
	Vector3 movement = (m_Camera.transform.right*moveHorizontal + m_Camera.transform.forward*moveVertical);
	rb.AddForce (movement * speed);
