Fix Mesh default properties

Author: RobLoach

include/MeshUnmanaged.hpp

@@ -39,6 +39,7 @@ class MeshUnmanaged : public ::Mesh {
         boneIds = nullptr;
         boneWeights = nullptr;
         boneMatrices = nullptr;
+        boneCount = 0;
         vaoId = 0;
         vboId = nullptr;
     }