species v0.5.1

• Fixed issue with the prior of distance when using FitModel.run_ultranest
• Enhancement with the integrated autocorrelation time that is calculated in Database.add_samples
• The plot_filename parameters in EmissionLine can be set to None to show instead of save a plot
• The default zorder is only added to the plot_kwargs dictionaries in plot_spectrum if not already included
• Updated notebook tutorials
• Style improvements and minor maintenance
• Updated setup.py