Add option for plot function to return figure and not display the figure itself.

I desire to use mplfinance with tkinter.

To do this most straight forwardly I desire an option to return the figure.

So adding an option returnfig, using code something like the below:

Adding to vkwargs:

    'returnfig': {'Default': False,'Validator': lambda value: isinstance(value, bool)},

And extending the "savefig" code something like the below:
Code something like the below:

if config['savefig'] is not None:
    save = config['savefig']
    if isinstance(save,dict):
        plt.savefig(**save)
    else:
        plt.savefig(save)
else:
    if config['returnfig'] is not None:
        save = config['returnfig']
        if save:
            return (fig)            
    # https://stackoverflow.com/a/13361748/1639359 suggests plt.show(block=False)
    plt.show(block=config['block'])