wpeterman/ResistanceGA: ResistanceGA-4.0-0

This release corresponds with the Applications paper to be published in Methods in Ecology and Evolution. Major updates include: • all_comb function facilitates a complete analysis of potential resistance surfaces, including single surface optimization, multisurface optimization of all single surface combinations, and bootstrap analysis of model support. • An updated vignette describes all major functions and their use • mlpe_rga is a general function to allow MLPE mixed effects models to be fit using standard lme4 formula syntax.