scope of ecto_opencv

[ethanrublee]

Suggesting less of a one to one mapping with opencv, and focus on:

io - video devices, disk r/w, pretty printing of cv mats
display - imshow, depth display, FPS
conversions - RGB2GRAY, RGB2LAB, etc... These are useful when the pipeline you are using expects a certain form of image
filters - common filtering operations on images

feature detectors are useful, but may be more special purpose. Calibration is cool to have, not sure where it fits in.