optional template arg for --print

[madsboddum]

Right now the output of --print is always formatted the same way: interrchange.iff@treefile.tre

It'd be cool if there was a way to specify a pattern instead, so it's customizable. That way the user can:

• Decide which information they want to see
• Decide where they want to see the information

So I might for instance be able to run the following:

$ toc -i sku0_client.toc --print

... and receive the normal output, but I could also run this:

$ toc -i sku0_client.toc --print "%file located in %tre"

... and thus format the output in a different way.