Fix a few things and refactor a little more

[PancakeTAS]

• Added icon
• Removed singletons from classes
• Fixed building process including workflow
• Update README.md, .gitignore, etc.
• Correct some of the javadocs
• Create a FUNDING.yml

I'd like to note that while I didn't change anything in the workflow, I also didn't test it, so I'm praying it still works.