Improved reliability of emerge logic (will now try a single-thread
make automatically as a fallback if the parallel emerge fails);
suppressed eix output, provided options to turn off perl-cleaner and
python-updater, now cleans unused distfiles by default, performs
a final @preserved-rebuild at end, and also warns if there is a built
kernel of a different version to that running.
Version moved to 1.0.4.