Better integration with power management scripts

[Richard Hughes]

Further to David's ideas, here are some of my ideas (shamelessly taken
from the ubuntu pmi and fedora pmscripts):

Create a /usr/share/hal/scripts/pm/hooks directory that distros and
vendors can dump files into that do things on resume and suspend, for
example:

* unloading certain modules and re-modprobing them if required
* stopping and starting certain services
* re-initialise the video of video cards as reqd.
* making the ibm led blink (echo "7 blink" > /proc/acpi/ibm/led)

And we only need one common pm helper script, for example returning what
kind of video adaptor (Intel, ATI, NVidia) you have or general useful
code we want to use in the pm hooks.

I think this is required as all the main distros have different ways of
doing this, for example pmi for ubuntu and pm-* for fedora, when all
this stuff is *really* simple and should be centralised in HAL so
vendors (hardware vendors like IBM or software vendors like Oracle)
could provide one file that works on any distro.

Any stuff like enabling bootsplash or doing other clever-stuff, one file
can just be dropped in /usr/share/hal/scripts/pm as required.

Comments? Please bear in mind the general idea is to make this easy for
a user to suspend and hibernate, not some political statement using HAL,
so please keep critique technical.

Richard.