2.0.0

1. Added core, for convenient API modification and integration(BETA).
2. Image functions were moved to a separate module(image_client.py)
3. Added new functions in image_client.py:
    - ImageClient.enhance - image enhancement
    - ImageClient.remove_watermark - removing watermarks
    - ImageClient.remove_background - removing background
4. Added new module utils/writing.py and new class/client WritingClient
5. New functions in utils/writing.py:
    - WritingClient.send_message:
        - parameters: input, instruction, model
        - returns: {'content': str}
    - WritingClient.get_models_list:
        - returns: list of available models