species v0.8.4

• Several small fixes in the retrieval framework (thanks @wbalmer!)
• Added flux_units parameter to get_mcmc_photometry
• Support for fitting multiple disk_teff and disk_radius parameters in FitModel
• Support for fitting the combined photometry of unresolved binary stars with different parallaxes
• Multiple improvements for fitting a combination of two spectra in FitModel
• Support for flux ratio prior for filters when fitting a binary system
• Check for NaNs in the uncertainties when adding a spectrum with add_object
• Updated plot_posterior for showing posteriors from binary systems
• Returning the individual binary components with get_mcmc_spectra
• Added support for coolTLUSTY Y dwarf spectra
• Tutorial for comparing data with a model grid of spectra
• Support for fitting separate ism_ext parameters for a binary system
• Support for PHOENIX Husser et al. (2013) models
• Major refactoring of FitModel, improved extinction accuracy, faster interpolation based on Teff prior
• Added optional database_file parameter to SpeciesInit
• Added fixed_param parameter to add_samples
• Added tag parameter and several improvements in get_residuals
• Changed the values added with inc_loglike to ln(L)
• Included chi2 and n_dof in ResidualBox
• Fixed indentation problem in CompareSpectra
• Robust implementation for filenames by using the pathlib instead of the os module
• Using pooch instead of urllib for downloading files
• Fixed bug in get_samples with reading normal priors
• Fixed bug with storing the log-likelihood after running run_multinest
• Fixed Windows issue with the Linder et al. (2019) isochrones
• Check for NaN and inf when calculating the goodness-of-fit statistic in CompareSpectra
• Exclude SpeX spectra that can not be flux calibrated when adding with add_spectra
• Updated dependency versions
• Overall code maintenance, many minor improvements, and updated tutorials