Support different panic headers

I have added support for multiple panic types.

The runtime `fatal error: fault` panic does not start with the text `panic:`, but it does crash the program. I believe panicwrap should also catch this.

Please note that I have not yet written tests for this change, I can't get the tests to work, for which I have opened a different issue(#3). I wanted to open a PR anyway so you could see what I'm working on and maybe give feedback.