fix trivial warnings

mainly unused parameter and unused function
some parameters are indeed used in a debug built, I used the
(void)(param) trick
warnings reported by clang 4

code/AssbinExporter.cpp

@@ -810,7 +810,7 @@ inline size_t WriteArray(IOStream * stream, const T* in, unsigned int size)
         }
     };
 
-void ExportSceneAssbin(const char* pFile, IOSystem* pIOSystem, const aiScene* pScene, const ExportProperties* pProperties)
+void ExportSceneAssbin(const char* pFile, IOSystem* pIOSystem, const aiScene* pScene, const ExportProperties* /*pProperties*/)
 {
     AssbinExport exporter;
     exporter.WriteBinaryDump( pFile, pIOSystem, pScene );