v5.2

Hi everyone, welcome to a new Clightd release!

This release spots a new feature, lots of fixes and some improvements;
Here's a list:

Backlight

• Added support for DDCUtil 1.0.0
• Changed signal is now emitted for external monitors too
• Improved external monitors handling

Idle

• GetClient now requires polkit auth

Keyboard

• A new keyboard API is added that allows to set keyboard Backlight level and timeout,
  have a look at the updated API wiki page: https://github.com/FedeDP/Clightd/wiki/Api#orgclightdclightdkbdbacklight

Generic

Moreover, thanks to @lgbaldoni, Clightd cmake file has seen some small fixes that allow easier packaging.
Finally, Clightd now builds on older glibc version.

I hope you'll enjoy it as much as I enjoyed developing it :)
Bye!