Release/0.2.16

[shima004]

close #150

This pull request refactors the road initialization and state persistence logic in both sample_road_detector.py and default_road_detector.py to improve code reuse and ensure consistent handling of target areas and priority roads across precompute, resume, and prepare phases.

Road initialization and state persistence:

• Introduced a new _initialize_roads method to encapsulate the logic for populating _target_areas and _priority_roads, reducing code duplication and improving maintainability. [1] [2]
• Changed the precompute and prepare methods to use _initialize_roads, ensuring consistent initialization of road-related sets. [1] [2]
• Updated the precompute method to serialize the computed road data (_target_areas and _priority_roads) to JSON, and the resume method to restore them from JSON, ensuring correct state restoration between runs. [1] [2]
• Moved the initialization of _target_areas and _priority_roads from the resume method to the new _initialize_roads method, and adjusted the logic to avoid redundant computation if already initialized. [1] [2]

These changes make the road detector modules more robust and maintainable by centralizing initialization logic and persisting state efficiently.