* support for incremental training
* fix SciBERT tokenier initialization from HuggingFace model
* updated HuggingFace transformers library to 4.25.1 and tensorflow to 2.9.3
* review the support of BPE tokenizers in the case of pre-tokenized input with the updated transformers library for most transformer models using it (tested with Roberta/GPT2, CamemBERT, bart-base, albert-base-v2, and XLM)
* addition of some model variants for sequence labeling (BERT_FEATURES, BERT_ChainCRF_FEATURES)