Drop DatabaseError _domain and _code properties that are no longer required by Xcode7b5.
Drop DatabaseError _domain and _code properties that are no longer required by Xcode7b5.

groue/GRDB.swift,hejunbinlan/GRDB.swift,zmeyc/GRDB.swift,carabina/GRDB.swift,zmeyc/GRDB.swift,zmeyc/GRDB.swift,hejunbinlan/GRDB.swift,groue/GRDB.swift,groue/GRDB.swift,hejunbinlan/GRDB.swift,carabina/GRDB.swift,groue/GRDB.swift,zmeyc/GRDB.swift