v0.2.3 - Inference BUG Fix

Fix some strange behaviors of model inference.

v0.2.2 - Embedder

1. Sync with the latest llama.cpp master branch.
2. Add LLamaEmbedder to support to get the embeddings only.
3. Add n_gpu_layers and prompt_cache_all param.
4. Split the package into main package + backend package.

v0.2.1 - Chat session, quantization and Web API

1. Add basic APIs and chat session.
2. Support quantization.
3. Add Web API support.