Add output options

[vintium]

We wanna be able to have an output file, because when you have 1000s of files the terminal output is just way too big. also that file could be in a custom format (which would be documented and easy to parse) so that it could be used by other programs. Don't eliminate writing to stdout though, because it's convenient. Make it so you have to choose with an option whether you want to write to a file or stdout. Something like -o <file> for output to file, -s for output to stdout.