forth: Use `?` not `try!`
Would cause an error in Rust 2018:
error: expected expression, found reserved keyword `try`
--> src/lib.rs:72:13
|
72 |             try!(self.step_term(term))
|             ^^^ expected expression
@@ -66,7 +66,7 @@ impl Forth {
fn run(&mut self) -> ForthResult {
while let Some(term) = self.code.pop_front() {
- try!(self.step_term(term))
+ self.step_term(term)?
}
Forth::ok()
