Changed about dialog and added mapping style checker

[viktor40]

• changed the URL in the about dialog to one pointing to the OrintheMC github page
• Check mappings against the style guide, see issue #4
  • Added a checker that checks Static Final fields to comply with our naming guide, meaning they have to be ALL_CAPS and separated by an _.
  • Checks that method names, non Static Final field names and argument names start with a lowercase letter
  • Checks that class names start with an upper case letter

Currently these are the colors that were chosen for this are: Light themes:

Dark themes:

If you have any issue with these colors you can comment on this PR.