reverting back to 16 digit precision export

having to import 17 digit floats likely leads to issues in many other apps

code/ColladaExporter.cpp

@@ -94,7 +94,7 @@ ColladaExporter::ColladaExporter( const aiScene* pScene, IOSystem* pIOSystem, co
 {
     // make sure that all formatting happens using the standard, C locale and not the user's current locale
     mOutput.imbue( std::locale("C") );
-    mOutput.precision(17);
+    mOutput.precision(16);
 
     mScene = pScene;
     mSceneOwned = false;