Fix comment — it's 'images', not 'stars'
Add new LEMON icon, designed by Sofía León
Set Sofía León's lemon as the GUI icon
Set icon as the logo for the About window
Add Sofía León to the list of Artists
Add icon image to the README
Add Sofía León
Use Sofía León's design as the LEMON icon

This merges branch 'add-lemon-icon'