Release 4 checklist

[shawnlaffan]

• [ ] Bump versions across all files
• [ ] Blog post - https://biodiverse-analysis-software.blogspot.com/2019/09/biodiverse-version-3.html
• [ ] Update versions.txt file
• [ ] Update news on github.io site (need to link to blog post)
• [ ] Post exe versions to downloads site
• [ ] Update link in Downloads wiki page
• [ ] Update SpatialConditions wiki
• [ ] Update Indices wiki
• [ ] Update ReleaseNotes wiki
• [ ] Deprecate Task:: files on CPAN (they have been superseded by the cpanfile)
• [ ] Tag release