enhance: checklist of part 3, dialogs, file handler test, and removed unused methods

What are the key features of this change

• Fixed the last things from the review of part 2.
• Added more tests for file handler.
• Deleted some unused methods
• Removed the double click to delete functionality as it was counter intuitive.
• Added better dialogboxes with the possibility for expandable information. (This could also be changed in the future to not only contain lists)
• Added a new iteration to README.md
• Images can now be put in a folder under resources.
• Added javadoc folder with deploying script to pages

closes: None

Size of change: big

Checklist

• Javadoc is added to methods and classes
• Tests are added to feature
• Build tool test passed