Add a project class prefix
Remove unused references to Specta from the Xcode project file
Silence Xcode version update recommendations
Add Apple's new CoreData.ConcurrencyDebug debugging launch argument to the project
For save blocks, change the BOOL "success" to "contextDidSave"

A state of NO passed to success was confusing to some users (rightfully so) — if a context has no changes and you call save on it, it will return NO via this parameter but nothing has actually gone wrong. Hopefully this is clearer.