Add fullscreen bypass support
This pull request adds support for automatically disabling redshift when a fullscreen application is detected, solving issue #548. There is a possibility to disable this function from command line with the option "-f 0".
Differing from #407, this implements the function in the redshift daemon. It does not use the EWMH because it is not reliable enough (confirmed poor compatibility with i3). No implementation has been made for Windows yet, but the code should still compile.
EDIT: Also, there is a SIGUSR2 and a checkbox in redshift-gtk to disable this function at any time.
EDIT: Multi-monitor support is a bit tricky and must be decided how it should work before it is developed. I think it must check if the focused window is fullscreen in its display and disable redshift for all displays, or make a per-display control, but I don't know if this is possible.