* Read hyper-parameters from HuggingFace-transformer config.json, if they exist, and fall back to guessing, like before otherwise.
This allows converting open_llama 3B and other non-standard model designs.
* Use F16 for memory_k and memory_v
* add command line switch to use f16 instead of f32 for memory k+v
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Co-authored-by: Ty Everett <ty@tyweb.us>