core: fixed multi-monitor support
desktops_i3: fix cpu spike in epoll loop

Fixes #75
Merge remote-tracking branch '5paceManSpiff/i3-hotfix' into develop
Merge remote-tracking branch '5paceManSpiff/monitor-hotfix' into develop
widgets/now_playing_mpris: event-driven updates

Use the player "metadata" event rather than a polling interval for
updating the widget. This event should be emitted when the track
changes.

If no player is passed, the widget will poll DBus for players every
second until it finds one.
Merge branch 'feature/mpris-events' into develop
widgets/magick: fix modulate argument order

The GM docs specify the ModulateImage() argument order to be brightness,
saturation, hue, but the actual order is brightness, hue, saturation.