Good morning. I've made some improvements to the Gentoo bash completion 
facilities.

Changes/Improvements:
- added "--world" to the list of options
- when completing on multiple options, only options that have not
   already been specified are listed
- fixed the behaviour [Canadian spelling] whereby options could be
   specified after packages
- "system" and "update" options do not appear if packages have been
   specified already, and must appear alone (this seems to make sense,
   but I'm not sure if this is the correct behaviour -- can you do
   something like "emerge --pretend update cat1/pkg1 cat2/pkg2"? --
   please let me know)

Zach