backward compatible load function for packed particle

Event/EventPacker/include/Event/PackedParticle.h

@@ -77,8 +77,16 @@ namespace LHCb {
     }
 
     template <typename T>
-    void load( T& buf, unsigned int /*version*/ ) {
-      Packer::io( buf, *this ); // identical operation until version is incremented
+    void load( T& buf, unsigned int version ) {
+      if ( version < 2 ) {
+        buf.io( key, particleID, measMass, measMassErr, lv_px, lv_py, lv_pz, lv_mass, refx, refy, refz, momCov00,
+                momCov11, momCov22, momCov33, momCov10, momCov20, momCov21, momCov30, momCov31, momCov32, posCov00,
+                posCov11, posCov22, posCov10, posCov20, posCov21, pmCov00, pmCov01, pmCov02, pmCov10, pmCov11, pmCov12,
+                pmCov20, pmCov21, pmCov22, pmCov30, pmCov31, pmCov32, firstExtra, lastExtra, vertex, proto,
+                firstDaughter, lastDaughter );
+      } else {
+        Packer::io( buf, *this );
+      }
     }
 #endif
   };