This commit removes gnome-base/gnome from the world file in favor of
the more slimmed down gnome-base/gnome-light. Because of this change
several other packages needed to be added to the world file to bring
back functionality that is lost from the slimmer install such as text
editor, email client, video player, etc.
package.gnome.use.{1, 2}: Adds required USE flags for mesa, clutter,
cogl, and libxcb.
