Release version 1.7.0

• Updated loader-saver module to support Windows file paths
• Added functions for saving and loading .json and .pickle files
• Improved methods for detecting points in line-pattern and chessboard images
• Added masking methods for removing unwanted points from calibration images
• Added methods for calibrating strong distortion (fisheye images):
  • Grouping points on strongly curved lines
  • Calculating the center of distortion using vanishing point approaches
  • Correcting perspective distortion