Fix: Improved compatibility with EDD Software Licensing 3.6
Fix: Improved PHP 7.3 and 7.4 compatibility.
Fix: When reviews was active, but FES was not, a fatal error occured in the settings.
Fix: Updated Slack icon on the welcome page.
Fix: Removed dependency of markdown parser for changelog by linking directly to the changelog.
Dev: Rebuilt the build system for Gulp 4.
