Assorted tweaks before a stable build
- Change "Mods..." to "Modules..." on the create new world window
- Correct wrong license header on three new files (and fix a comment)
- Add another image to the readme and shrink the existing one (and fix its path)
- Reminder in the Gradle logging that natives get cleaned now and may have to be re-extracted
- Updated README some including a module summary plus new contributor entries for the credits
Small README tweak
Forgot to doc Portals
Logging tweak