Ability to deselect open source libraries from warnings

[elizaaverywilson]

This is a great project, but you could you add the ability to not include certain directories in the warnings? I don't want to get warned about open source libraries having typing problems :)

[tewha]

I don't think there's any way to get Xcode to do this. What I do is put the open source libraries in a single static library. Then I don't use a configuration file for that static library.

I'm going to leave this issue open because it's ANOTHER thing that should probably be documented. :)