species v0.5.4

• Support for Saumon & Marley (2008), Baraffe et al. (2015), and NextGen isochrones
• Added get_cooling_curve, get_filters, get_mass, and get_radius methods to ReadIsochrone
• Ignore parameters in ReadModel that are not mandatory
• Bug fix with reading the Sonora Bobcat evolutionary models
• Support for Mg2SiO4 cloud species in AtmosphericRetrieval
• Added grid_hspace parameter to plot_spectrum
• Added get_magnitude method to ReadRadtrans
• Support for rad_vel and vsini parameters in ReadRadtrans
• Added inc_log_mass parameter to plot_posterior
• Notebook tutorial for ReadIsochrone
• Minor maintenance and improvements to code and documentation