New features

• Initial support of encoder-only Transformer model via a new class ctranslate2.Encoder
• Update the Transformers converter to support the Falcon models
• Add a generation argument static_prompt to optimize the execution for models using system prompts: the model state for this prompt is cached and reused in future calls
• Support early stopping in greedy search when the callback function returns True
• Make the layer norm epsilon value configurable in the model configuration file config.json
• Add Tanh as a possible activation function

Fixes and improvements

• Fix a performance issue when running models using ALiBi on the GPU
• Fix application of the rotary embeddings when the multi-query attention is used
• Fix conversion of Marian models using tied-embeddings-all: false
• Remove use_fast argument when loading Hugging Face tokenizers to use the default tokenizer for the model