Use proper deallocator for SecKeychainItemCopyAttributesAndData

This was found using clang's static analyzer.
Opening bundle item chooser will reset selection to first row
Opening folder after session restore would not see it as open

When opening a folder we test against the ‘projectPath’ property (on already open window controllers), but this is not setup until we have an open document, and documents are opened using a background queue, so code running in the same event loop cycle as the session restore, will not get the proper value for this property.

The problem this fixes is: open /path/to/foo and quit TextMate. Now drag /path/to/foo to TextMate’s app icon. TextMate would first restore session (which includes /path/to/foo) and then open /path/to/foo (not seeing the restored folder as being /path/to/foo due to the uninitialized ‘projectPath’ property).
Use proper deallocator for SecKeychainItemCopyAttributesAndData