RFE: automate simple adding and changing of info clues

I envision bugxml doing this in the future:

 bugxml -sa totem "libxine.so" "This is probably a libxine problem. Ask the user to check if xine-ui has the same problem."

The tool would then
 * check if ./packages/totem.info exists
 * if not, check for ./totem.info
 * if one of them exists, add <clue><op>libxine.so</op><info>This is probably a libxine problem. Ask the user to check if xine-ui has the same problem.</info></clue> nodes below the <clues> node.
 * if not, create a new file.

This of course only handles the simple cases, but it'd be a good improvement for our workflow.