Fix design tool export bug (thanks neurofun)

https://forum.pjrc.com/threads/48304

gui/red/main.js

 									var src_name = make_name(src);
 									var dst_name = make_name(dst);
 									if (j == 0 && parts[1] == 0 && src && src.outputs == 1 && dst && dst._def.inputs == 1) {
-										cpp += src_name + ", " + parts[0];
+										cpp += src_name + ", " + dst_name;
 									} else {
 										cpp += src_name + ", " + j + ", " + dst_name + ", " + parts[1];
 									}