Save QA output so that it can be conveniently displayed

Save QA output so that it can be conveniently displayed
in $EDITOR while the user creates a commit message.
Otherwise, the user would not be able to see this output
once the editor has taken over the screen.

Output is done through a formatter object where it is
captured for later use. A file-like object that behaves
something like the portage.output.colorize() function is
used to transfor style identifiers from the formatter
framework into actual console codes.

(trunk r8925)

svn path=/main/branches/2.1.2/; revision=8926