Rollback to Webpack 3...

...until plugins are fully updated for Webpack 4.

Author: philwareham

dist/four-point-seven/manifest.json

@@ -5,4 +5,4 @@
   "description": "The default theme shipped with Textpattern CMS 4.7.",
   "author": "Team Textpattern",
   "author_uri": "https://github.com/textpattern/textpattern-default-theme"
-}
+}