message: Export more symbols from libvisionaray-common
diff: #include <string>
  +#include "export.h"
  #include "image_base.h"
  namespace visionaray
  @@ -17,7 +18,7 @@ class tga_image : public image_base
  {
  public:
  - bool load(std::string const& filename);
  + VSNRAY_COMMON_EXPORT bool load(std::string const& filename);
  };
  