Api implementation 0.1

[RafaDdS]

This adds the functionality currently present on https://github.com/RafaDdS/OpenCVGodot.

Implementation of:

• Full Video Capture module
• Some core methods for mat manipulation
• Basic functionality on Mat, with conversion to Godot image
• Imread from ImgCodecs
• File of CVConsts

[matt-s-clark]

Great work! The only suggestion I have is to implement clang-format in your editor so that the code is consistently formatted.

It looks like your clang-format is working correctly, it's just the rules don't always make the code look very elegant if new lines aren't applied in a good place. I added new lines where I think they improve readability. Some of the changes look better than others, particularly the longer signatures - however the shorter signatures have less of a readability issue.