fix AssertionError: First token is not <cls> token value in extract_and_plot_cell_embeddings.ipynb

further emphasize different token dictionaries in examples

Add classifier module and examples

Add option to output embs as tensor

Fixed error with perturbing individual genes and updated ways to specify cell_states_to_model (#146)

Rename heatmap legend to be correct label

Add function to extract and plot cell embeddings