Cleanup plugin code base

[cpotter302]

code refactoring, review before publishment and hand over to eclipse #89

[dangelic]

Add the following:

• ESLint configuration
• Prettier
• Husky for pre-commits (runs prettier before every commit is done)
• Commenting of each module
• Outsourcing of hard-code

[dangelic]

in review by @cpotter302 ... merci 👍