Follow-up to 97001710c06ed7053d18c8baaac602eb563b64b3

- Added missing license note and error message to the script-checker
  bash script
- Added Script-Checker.applescript. Open in Applescript Editor and save
  as .app bundle in order to use it. It's not pretty, but it works.

Signed-off-by: Haru <haru@dotalux.com>
Follow-up to 97001710c06ed7053d18c8baaac602eb563b64b3

- Added script-checker.bat launcher for Windows.