added some more required DLL exports for external trackers

Note the disabled warning in TrackedObject. Otherwise, the whole STL container needs to be exported to the DLL, which is very problematic for a std::map.
Just disabling the warning works in this case, because the member is private and can not be accessed directly from outside of the DLL anyway.

For more info on this, see https://support.microsoft.com/en-us/kb/168958

biotracker/serialization/ObjectModel.h

@@ -3,6 +3,8 @@
 #include <cereal/cereal.hpp>
 #include <cereal/access.hpp>
 
+#include "util/platform.h"
+
 namespace BioTracker {
 namespace Core {
 
@@ -10,7 +12,7 @@ namespace Core {
 * class representing the object/animal
 * which is to be tracked
 */
-class ObjectModel {
+class BIOTRACKER_DLLEXPORT ObjectModel {
   public:
     virtual ~ObjectModel() = 0;
 };

biotracker/serialization/TrackedObject.h

@@ -11,13 +11,14 @@
 #include <cereal/types/map.hpp>
 #include <cereal/types/vector.hpp>
 
+#include "util/platform.h"
 #include "ObjectModel.h"
 #include "types.hpp"
 
 namespace BioTracker {
 namespace Core {
 
-class TrackedObject {
+class BIOTRACKER_DLLEXPORT TrackedObject {
   public:
     TrackedObject(size_t id);
     //TODO: check if default ctor is really necessary for cereal
@@ -73,8 +74,17 @@ class TrackedObject {
   private:
     size_t _id;
     size_t m_maximumFrameNumber;
-    std::map<size_t, std::shared_ptr<ObjectModel>> _objectsByFrame;
 
+#ifdef _MSC_VER
+    // Disable DLL export warning for this member. This is only possible
+    // because the member is private and can not be accessed directly when using the DLL anyway.
+#  pragma warning( push )
+#  pragma warning( disable: 4251 )
+#endif
+    std::map<size_t, std::shared_ptr<ObjectModel>> _objectsByFrame ;
+#ifdef _MSC_VER
+#  pragma warning( pop )
+#endif
     friend class cereal::access;
     template <class Archive>
     void serialize(Archive &ar) {

biotracker/util/platform.h

@@ -6,8 +6,10 @@ This macro must be used to mark all symbols that should be exported to a DLL.
 #ifdef _MSC_VER
 #ifdef BUILD_BIOTRACKER_DLL
 #define BIOTRACKER_DLLEXPORT __declspec(dllexport)
+#define BIOTRACKER_EXPIMP_TEMPLATE
 #else
 #define BIOTRACKER_DLLEXPORT __declspec(dllimport)
+#define BIOTRACKER_EXPIMP_TEMPLATE extern
 #endif
 #else
 #define BIOTRACKER_DLLEXPORT