Created image file format README with official recommendations

[oeed]

The main issue involves the official recommendations #6

I personally do not think the paint image format should be a recommended format. Although it has not yet been publicly been released, UCG (by ardera) is a far more efficient format (honestly, it can shrink file sizes to below 20% of the original size).

The issue is, however, unless Dan implements UCG in the paint program (which he should IMO) people are going to use paint, especially until there's an editor available for UCG images.

As UCG is as efficient in lower sizes, perhaps we only recommend paint for small images?

[viluon]

One way I thought of the official recommendation idea #6 was that this repository and its maintainers would be regarded as an authority by the rest of the community. Saying that UCG is the recommended image format would be equal to saying that it should be implemented in every painting program (which is my honest opinion) and every program that does not follow the recommendations should be essentially fixed to do so. As soon as UCG is standardized, I would recommend it.

[oeed]

The question is though, do we flat out not recommend paint at all? The problem with UCG is the code is actually pretty complicated. It uses Huffman trees and reading & writing both take a few hundred lines rather than the single function call that's built in to paintutils.

Ideally @dan200 woould change paintutils to use the UCG format, but we can't guarantee that at all.

[viluon]

If there was an official format for data transmission in CC that you knew was flawed, would you recommend it? If UCG is superior, there is no point in recommending NFP instead. Both can be recommended, but I would prefer UCG. Don't forget that the standard proposal should already contain utilities and example code to deal with complex algorithms, and users can really just copy - paste that.

[oeed]

In that case yeah, I'd say we shouldn't recommend the format.