SF Shock Bridge Theme per Angela Ziegler

This is a purely aesthetic extension that changes the user's Firefox theme between three different options based on time of day (Daylight Theme from 9am to 7pm, Nighttime Theme from 9pm to 7am, and Dawn/Dusk themes in between). Features animated header art of the Golden Gate Bridge - it's a very subtle animation, don't worry!

Future updates may include more headers and themes for local weather patterns, the ability to set the time of day, or longer and smoother animations.