Tweak default icewm preferences

Attention: this patch is applied in the %build phase, because it patches
a file generated by ./src/genpref. To edit the patch:

  quilt setup icewm.spec
  cd icewm-<version>
  quilt push -a
  ./configure <options from the spec>
  make -C src genpref
  ./src/genpref >lib/preferences
  quilt import -p0 patches/icewm-preferences.patch
  quilt push
  vi lib/preferences
  quilt refresh
---
 lib/preferences |   12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

--- lib/preferences.orig
+++ lib/preferences
@@ -509,7 +509,7 @@
 # NewMailCommand=""
 
 #  Command to lock display/screensaver
-# LockCommand=""
+LockCommand="xscreensaver-command -lock || xlock -mousemotion"
 
 #  Command to run on clock
 # ClockCommand="xclock -name icewm -title Clock"
@@ -533,10 +533,10 @@
 # LogoutCancelCommand=""
 
 #  Command to shutdown the system
-# ShutdownCommand=""
+ShutdownCommand="dbus-send --system --print-reply --dest=org.freedesktop.ConsoleKit /org/freedesktop/ConsoleKit/Manager org.freedesktop.ConsoleKit.Manager.Stop"
 
 #  Command to reboot the system
-# RebootCommand=""
+RebootCommand="dbus-send --system --print-reply --dest=org.freedesktop.ConsoleKit /org/freedesktop/ConsoleKit/Manager org.freedesktop.ConsoleKit.Manager.Restart"
 
 #  Command to run on CPU status
 # CPUStatusCommand="xterm -name top -title Process\ Status -e top"
@@ -1280,19 +1280,19 @@ WorkspaceNames=" 1 ", " 2 ", " 3 ", " 4
 #
 
 #  Display desktop background centered and not tiled
-# DesktopBackgroundCenter=0 # 0/1
+DesktopBackgroundCenter=1 # 0/1
 
 #  Support for semitransparent terminals like Eterm or gnome-terminal
 # SupportSemitransparency=1 # 0/1
 
 #  Desktop background scaled to full screen
-# DesktopBackgroundScaled=0 # 0/1
+DesktopBackgroundScaled=1 # 0/1
 
 #  Desktop background color
 # DesktopBackgroundColor="rgb:00/20/40"
 
 #  Desktop background image
-# DesktopBackgroundImage=""
+DesktopBackgroundImage="/usr/share/wallpapers/default-1600x1200.jpg"
 
 #  Color to announce for semi-transparent windows
 # DesktopTransparencyColor=""