add enum PropertyType, so that properties can be restored from .om files

src/OpenMesh/Core/IO/writer/OMWriter.cc

@@ -620,11 +620,18 @@ size_t _OMWriter_::store_binary_custom_chunk(std::ostream& _os,
   // 2. property name
   bytes += store( _os, OMFormat::Chunk::PropertyName(_bp.name()), _swap );
 
-  // 3. block size
+  // 3. data type
+  OMFormat::Chunk::PropertyType type;
+
+
+
+  bytes += store(_os, type, _swap);
+
+  // 4. block size
   bytes += store( _os, _bp.size_of(), OMFormat::Chunk::Integer_32, _swap );
   //omlog() << "  n_bytes = " << _bp.size_of() << std::endl;
 
-  // 4. data
+  // 5. data
   {
     size_t b;
     bytes += ( b=_bp.store( _os, _swap ) );