Share xfce4-session and xfce4-power-manager code

[Nick Schermer]

Folks,

There is a lot of consolekit/polkit code duplicated in
xfce4-power-manager/xfce4-session. The code in xfce4-session is also a
bit of a mess since everything is in 1 file, xfce4-power-manager seems
to be more ordered in this aspect. To resolve this there are a couple
of possible solutions:

1) Remove all shutdown/suspend handling from xfce4-session and use
xfce4-power-manager for this (it can act as a dbus service).
2) Share code in a library. It pulls too many individual modules, so
this will most likely end up in xfce4-session or xfce4-power-manager.
    - Lib in xfce4-power-manager: most move to core.
    - Lib in xfce4-session: ugly dep for xfce4-power-manager.

Personally I prefer the first option. We might need to extend
xfce4-power-manager so support sudo for bsd systems or let
xfce4-session fallback on that if xfce4-power-manager is not found
(how good does it actually function on *bsd?). For Ali this means if
xfce4-power-manager is in core he must follow the release model, but
that won't be a real problem I think.

Anyhow, open for discussion!

Nick