Add couple of libraries needed for calculating sunset/sunrise times - I could use PyEphem, but that either required installing PIP or python-dev, and I didn't want to go down that rabbit hole right now.
Update sunrise to return datetime.datetime

This allows datetime differences to be easily calculated.
Add details of where script copied from
First attempt at the main functionality

Committing and pushing in case I make the RPi unusable!

sunrise: modified to take "tomorrow" arg to make it easier to calculate the next sunrise

tempus_fugitd: move all decision making to one place, add a way to block reloads (via magic file on USB), and do the timer handling to cause us to reload.  tidy upfix EXIF GPS info,