Be sure to canonicalize signal names passed to `connect`

Closes #43

src/gen/instance_ext.rs

@@ -89,7 +89,8 @@ pub fn slot_trait_impls<'ast>(names: &Names, slots: &[Slot<'ast>]) -> Vec<TokenS
                 let connect_signalname = signals::connect_signalname(signal);
                 let signalname_trampoline = signals::signal_trampoline_name(signal);
                 let sig = &signal.sig;
-                let signalname_str = format!("{}", sig.name);
+                let signalname_str = signals::canonicalize_signal_name(&sig.name.to_string())
+                    .expect("rust identifiers should always be canonicalizable");
                 let input_types = signal.sig.input_arg_types();
                 let output = &sig.output;