closes https://github.com/assimp/assimp/issues/892: add own to_string

implementation.

code/ColladaParser.cpp

@@ -51,12 +51,14 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include "ColladaParser.h"
 #include "fast_atof.h"
 #include "ParsingUtils.h"
-#include <memory>
-#include "../include/assimp/DefaultLogger.hpp"
-#include "../include/assimp/IOSystem.hpp"
-#include "../include/assimp/light.h"
+#include "StringUtils.h"
+#include <assimp/DefaultLogger.hpp>
+#include <assimp/IOSystem.hpp>
+#include <assimp/light.h>
 #include "TinyFormatter.h"
 
+#include <memory>
+
 
 using namespace Assimp;
 using namespace Assimp::Collada;