Caffeine is a little daemon that sits in your systray, and prevents the
screensaver from showing up, or the system from going to sleep. It does
so when an application is fullscreened (eg: youtube), or when you click
on the systray icon (which you can do, when, eg: reading).

This is a fork of Caffeine 2.4, since later versions dropped support
for the systray icon in favour of automatic detection of fullscreen
apps only.

setuptools-scm is only required as a build dependency and can be
skipped if you would rather have it automatically grabbed from
pypi.python.org during the build process.