Actually combine the XKB options into a string, rather than just repeatedly
writing a comma.
(cherry picked from commit da893908feb2dcf7c22420b3426ab3ac65c7ca99)
Don't use our DBusError for property getting, because we simply don't care:
this fixes D-Bus error spew to stderr. Thanks Michel Dänzer for debugging
and testing.
Add support for HAL-based hotplugging, in which we just get the list of
input devices and properties from HAL. Requires an FDI which is not yet
in mainline HAL.
