Initial canny preprocessing

[lole-elol]

Added initial canny edge detection preprocessing Closes #8

Omitted un-distorting since we need to introduce a cropping first to avoid getting a black surrounding. Canny will detect the border between the image and the surrounding as an edge, unfortunately.

1. Gaussian blur (improves canny edge detection)
2. Extract edges with double threshold (min, max)
3. combine original un-blured image with extracted edges via Gaussian blur to smooth hard edges.

Results point cloud for images 7 & 8 (seemed to perform best): pointCloud with properties:

 Location: [690x3 single]
    Count: 690
  XLimits: [-1.1758 2.9632]
  YLimits: [-3.0545 0.2581]
  ZLimits: [0.2695 7.4523]
    Color: [690x3 uint8]
   Normal: []
Intensity: []

Results point cloud for images 9 & 10 (Unfortunately very bad, maybe insufficient cam calibration): pointCloud with properties:

 Location: [185x3 single]
    Count: 185
  XLimits: [-3.3488 0.2463]
  YLimits: [-1.4387 0.2121]
  ZLimits: [0.2639 14.7375]
    Color: [185x3 uint8]
   Normal: []
Intensity: []

[danielsanjosepro]

Already doing this in #14