Add support for VST2 effBeginLoad{Bank,Program}

A user reported that REAPER was using these on the REAPER forum, but I
have not been able to reproduce that. And they went MIA after posting
about it. But hopefully this helps.

src/common/serialization/vst2.h

@@ -444,6 +444,7 @@ struct Vst2Event {
                                  VstIOProperties,
                                  VstMidiKeyName,
                                  VstParameterProperties,
+                                 VstPatchChunkInfo,
                                  WantsVstRect,
                                  WantsVstTimeInfo,
                                  WantsString>;
@@ -642,6 +643,15 @@ void serialize(S& s, VstParameterProperties& props) {
     s.container1b(props.future);
 }
 
+template <typename S>
+void serialize(S& s, VstPatchChunkInfo& info) {
+    s.value4b(info.version);
+    s.value4b(info.pluginUniqueID);
+    s.value4b(info.pluginVersion);
+    s.value4b(info.numElements);
+    s.container1b(info.future);
+}
+
 template <typename S>
 void serialize(S& s, VstRect& rect) {
     s.value2b(rect.top);