Allow overriding sending behaviour for VST2 events

Now we can implement mutual recursion for VST2 plugins. Wish we didn't
have to.

src/common/communication/vst2.cpp

@@ -70,3 +70,10 @@ intptr_t DefaultDataConverter::return_value(const int /*opcode*/,
                                             const intptr_t original) const {
     return original;
 }
+
+EventResult DefaultDataConverter::send_event(
+    boost::asio::local::stream_protocol::socket& socket,
+    const Event& event) const {
+    write_object(socket, event);
+    return read_object<EventResult>(socket);
+}