bugfix: copy binding before run

Copy the binding struct before running it and use this copy to emit the
binding event.

This fixes a crash when the command `reload` is used in a binding when
the binding event is emitted.

include/bindings.h

@@ -60,6 +60,11 @@ void switch_mode(const char *new_mode);
  */
 void check_for_duplicate_bindings(struct context *context);
 
+/**
+ * Frees the binding. If bind is null, it simply returns.
+ */
+void binding_free(Binding *bind);
+
 /**
  * Runs the given binding and handles parse errors. If con is passed, it will
  * execute the command binding with that container selected by criteria.