PHOEBE 2.4.0

• add support for differential evolution optimizer solver
• add support for differential corrections optimizer solver
• optimizers: ability to continue runs from previous solutions (for most optimizers)
• improvements to geometry and ebai estimators to use ligeor as a new built-in dependency
• gaussian processes now use celerite2 or scikit-learn instead of celerite
• emcee sampler: additional plotting styles to check for convergence, checks to ensure starting sample is physical, and added ability to continue a previous run from any arbitrary iteration in a previous run
• new support for running jobs on external servers via crimpl
• clarified distinction between chi2 and mle