Add acknowledgements and citations

[dmarx]

try to include acknowledgements for "indirect" contributors as well, i.e. people whose names don't appear in commits because their code was incorporated from a shared notebook or something like that.

[dmarx]

• vqgan+ clip: https://arxiv.org/abs/2204.08583
• semantic image target: https://arxiv.org/pdf/2110.12427.pdf
• OpenAI/CLIP: https://arxiv.org/abs/2103.00020
• VQ-VAE: https://papers.nips.cc/paper/2017/hash/7a98af17e63a0ac09ce2e96d03992fbc-Abstract.html

[dmarx]

dribnet - pixel art