Don't unnecessarily duplicate strings.
Move declaration closer to use.
Make 'hard' default paper size the first listed in paperspecs.
Refactor systempapername for clarity.
Remove need for math library.
Add definition of Letter size in whole mm to match GNU libc's langinfo definition.
Remove useless check for file existing.
Turn assert failure into error message.
Make whitespace-clean.
Fix memory leaks.
Fix operation with no command-line argument, only options.