Reduce object allocations in MotionEvent's direction computation

[capdevon]

This PR introduces a minor but impactful performance optimization within the MotionEvent class.

Previously, the computeTargetDirection() method repeatedly created new Quaternion objects (q and q2) on each call when handling Path and PathAndRotation direction types. This constant object allocation can lead to unnecessary garbage collection overhead, particularly in performance-critical game loops or animations.

To address this, I've refactored the method to utilize a single, reusable Quaternion class member variable (tempRotation). By reusing this existing object, we significantly reduce memory allocations and subsequent garbage collection cycles, resulting in a modest but noticeable performance improvement, especially when many MotionEvents are active or when the method is called frequently.