Cleanup: modeline, fix comments, fix arg processing

Signed-off-by: Dan Mick <dan.mick@inktank.com>
Add explicit "used" and "unused" flags; output one or both sections

Signed-off-by: Dan Mick <dan.mick@inktank.com>
Fix demangled-sym parsing (maybe move to pyelftools to avoid this)

Signed-off-by: Dan Mick <dan.mick@inktank.com>