The missing "; @:" at the end of the otherwise recipeless rule
resulted in target graph being broken; I should have checked this
when introducing these aliases (the intent was to reduce noise).

It's configured by plymouth feature when needed;
install2 bootargs support is generalized a bit
to become stage2 one as was intended anyways.

An initial draft of it was done half a year ago but several tricky
thingies had kept the code from showing up as it was rather brittle
and incomplete.

This implementation involves quite a few changes all over the place
but finally works good enough for live and installer images.

Please pay attention to the versions of these packages:
- installer-feature-setup-plymouth (0.3.2-alt1+)
- branding-altlinux-sisyphus (20110706-alt2+ if used)
- plymouth (0.8.3-alt20.git20110406+)

See also:
- http://www.altlinux.org/Branding
- http://www.altlinux.org/Plymouth