structured_light: GreyCodePattern 16-bit support and performance improvements

- Vastly improve performance of the GreyCodePattern structured light algorithm by leveraging built-in OpenCV functions and parallel code instead of raw loops, at the cost of a bit more memory (decoding a set of 96 5320x4600 images acquired using stereo cameras goes from taking ~100 seconds to taking ~2.5 seconds, in release mode)
- Automatically gain the ability to decode 16-bit images (switching from raw loops and uchar-indexing to OpenCV functions gives this for free)

Manual testing was done to ensure that the calculated results are correct, both for generation of the patterns and for decoding, in both Debug and Release mode, using real world data.

Author: Atari2