1.6.0

• Release of new package to convert grid maps to signed distance fields.
• Several new grid map filters for flexible processing of grid maps:
  • Math expression filter based on EigenLab,
  • Sliding window math expression filter,
  • Normal vector and curvature filter,
  • Color map, normal color, light intensity filter,
  • ... and more!
• Added new sliding window iterator.
• Added new thickenLine(), triangulation, and bounding box method to polygon.
• Fixed compatibility issue with OpenCV 3.
• Several bugfixes and performance improvements.