This commit adds a new program, plymouth-upstart-bridge,
the listens for upstart state changes and sends them to plymouth,
or prints them out as appropriate.
The scripts hard-coded the paths for LIBEXECDIR and DATADIR, unless
passed as environment variables. Instead of doing this, which breaks
if plymouth is installed outside of /usr, set these derived from the
configure $libexecdir and $datadir variables just as we do for
pkg-config, etc.
Since we use so many variables, it makes more sense to generate these
scripts from config.status rather than having special Makefile rules
for them.
Some of the plugins (well, the glow plugin) would be a lot more
versatile if they could be reused for multiple splashes with different
images.
This commit splits boot splashes into two parts, the plugin engine which
does all the dirty work, and the theme which says which plugin to use
and optionally how the plugin should work (using plugin specific
key/value pairs)
The old approach of including the same source files into
multiple places is less than pretty. But moving the code
to libply didn't seem right either, since libply is fairly
generic and could in theory get swapped out with a standard
runtime at some point.
Also, exposing libplybootsplash as an external library will
facilitate creating out of tree splash plugins.
