fixed regression in background threading support
restored py-appscript manifest files
added macOS 10.14 Automation permissions APIs to py-appscript; deleted objc-appscript (superseded by AppleEventBridge)
[objc-appscript] fixed missing headers
[objc-appscript] updated project (10.6+, no GC)...
[objc-appscript] updated project (10.6+, no GC)...