Macro dynerr::logged_panic

macro_rules! logged_panic {
    ($e: expr) => { ... };
    ($e: expr, $log:expr) => { ... };
}

logs error to file then panic!
if no file supplied then defaults to "event.log"

#Example

example(9).unwrap_or_else(|e|logged_panic!(e));
example(9).unwrap_or_else(|e|logged_panic!(e), "mylog.log");