jtschindler/sculptor: Sculptor version 0.3-beta.0

Updates from 0.2-beta.0 to 0.3-beta.0: New capabilities & additions Added propagate option. One can now decide whether the previous SpecModel is subtracted from the spectrum or divided out. Added documentation to the Masks & Models module Added non-parametric measurements that allow to determine the median velocity or velocity width (W80, W90) or a emission line model. Documentation for the non-parametric methods is available. Added capabilities to analyze the output files of resampled spectral fits. Documentation is available in the SpecAnalysis module, but not example notebook exists at the moment. These functions work similar to analyze_mcmc_results in "Scripting Sculptor 03 - Fitting and Analzying models using MCMC". Bug fixes Fixed an issue with iron template dispersion and flux density units that would make the code crash when saving any model with an iron template. Replaced the astropy blackbody_lambda function (deprecated) with the astropy.modeling.models BlackBody function, effectively removing the astropy deprecation warnings. When loading a SpecFit folder redshift, dispersion/flux density limits and fit method are now correctly updated in the SpecFit GUI. Fixed an issue with saving SpecModel and SpecFit classes that lead to warning messages within numpy. Fixed an issue where the dispersion/flux density composite units (CompositeUnit) of template models (e.g. iron templates) would lead to error messages and abort the code