fix some compile warnings:

- passing NULL to non-pointer
- unused vars
- unused function
- order of init
- parentheses

code/Exporter.cpp

@@ -120,7 +120,7 @@ Exporter::ExportFormatEntry gExporters[] =
 #endif
 
 #ifndef ASSIMP_BUILD_NO_ASSBIN_EXPORTER
-	Exporter::ExportFormatEntry( "assbin", "Assimp Binary", "assbin" , &ExportSceneAssbin, NULL),
+	Exporter::ExportFormatEntry( "assbin", "Assimp Binary", "assbin" , &ExportSceneAssbin, 0),
 #endif
 };