using UnityEngine;
using System.Collections;

[RequireComponent(typeof(CharacterController))]  
public class RelativeMovement : MonoBehaviour {
...
public float moveSpeed = 6.0f;

private CharacterController _charController;

void Start() {
    _charController = GetComponent<CharacterController>(); 
}

    void Update() {
        ...
          movement.x = horInput * moveSpeed;    
          movement.z = vertInput * moveSpeed;
          movement = Vector3.ClampMagnitude(movement, moveSpeed);   
          ...
        }

        movement *= Time.deltaTime;            
        _charController.Move(movement);
    }
}
