Add support for binding actions to buttons.

Example:

[bindings]
ps+left = prev-profile
ps+right = next-profile
ps+up = load-profile kbmouse

[profile:kbmouse]
bindings = exec

[bindings:exec]
ps+circle = exec echo $name $report.battery
ps+cross = exec-background firefox
Fix multiple controller crash.
hidraw: Unify the constructors.
Add $device_addr to action binding vars.
hidraw: Get the bluetooth MAC on USB devices aswell.
Ignore already connected devices.

No more double device when connecting USB!
actions: Fix the exec-background binding action.
actions: Improve button combo usage.

Only require last button to be released before triggering a action
instead of the whole combo.