ver 2.91.5:
Properties:
- Make dialogue parenting work for errors

Library:
- Use BluetoothClient to track default adapter
- Don't free request_key and passkey in agent reply functions
- Set log domain to differentiate library messages from the lib's ones

Applet:
- Fix crash in bluetooth_applet_create_device_from_iter()
- Fix crash when creating an agent
- Fix crash when unref'ing a DBusGMethodInvocation
- Fix crash when there's no default adapter

Moblin:
- Fix compilation of the Moblin front-end