Adds an ivar reference in QSPreferencePane to the NSArray of top-level objects instantiated by the NIB.
Updates the QSPreferencePane to manually use Core Foundation to release the top-level NIB objects, to avoid using the improved 10.8-only NIB-loading method, while still ensuring the top-level objects are properly released when using ARC.
Merge branch 'leaks' of https://github.com/quicksilver/Quicksilver into leaks