Fine-tuning

The train command of larvataggerand similar scripts admits argument--fine-tune, to further train an already trained tagger. Under the hood, with this argument, trainswitches totagging-backend finetuneinstead oftagging-backend train`.

For example, MaggotUBA loads an existing tagger from the models directory instead of initializing a new tagger with a pristine classifier and a pretrained encoder loaded from the pretrained_models directory.