Added thread debugging launch arguments for Core Data, but it seems they may be ignored in recent OS.
Small change to prevent a NSManagedObject being accessed on the wrong thread. The access was purely a retain, no access to properties, but better to be safe than sorry.
Set undoManager on a few contexts to nil.

Also set a merge policy for the event store context. It should not be needed, but Kevin Hoctor is getting conflicts between PSC and Store global ids on 10.9. This should not be possible, because there is only one MOC accessing the store, but it seems to happen when a save interrupts a merge.

This issue has been reported for 10.9 online, and seems to be a genuine Apple bug (http://lists.apple.com/archives/cocoa-dev/2005/Aug/msg00899.html).