Fixed build warnings on MSVC14 x64 in the CSM loader.

code/CSMLoader.cpp

@@ -179,7 +179,7 @@ void CSMImporter::InternReadFile( const std::string& pFile,
                     nda->mNodeName.length = (size_t)(ot-nda->mNodeName.data);
                 }
 
-                anim->mNumChannels = anims_temp.size();
+                anim->mNumChannels = static_cast<unsigned int>(anims_temp.size());
                 if (!anim->mNumChannels)
                     throw DeadlyImportError("CSM: Empty $order section");