message: Add warning when a script completes with a statement in memory
diff: @@ -277,6 +277,12 @@ impl<'a> Shell<'a> {
  }
  self.on_command(&buffer.consume());
  }
  + // The flow control level being non zero means that we have a statement that has
  + // only been partially parsed.
  + if self.flow_control.level != 0 {
  + eprintln!("ion: unexpected end of script: expected end block for `{}`",
  + self.flow_control.current_statement.short());
  + }
  }
  pub fn terminate_quotes(&mut self, command: String) -> Result<String, ()> {
  