Quaternion EKF with Expanded State Vector

Expanded the state vector to include gyro bias to mitigate prediction drift

v2.0.0: Quaternion-Based EKF

What's New in v2.0.0

• Replaced Euler-angle-based orientation estimation with quaternion-based estimation.
• Solved gimbal lock and angle wrapping issues.
• Added dynamic and measurement models for quaternion-based EKF.
• Updated README with detailed explanations and usage instructions.
• Implemented rust-ekf in a real-world robotics project and showed results