factoring out record names as const

core/PluginsArchiver.php

plugins/Actions/Archiver.php

plugins/CustomVariables/API.php

plugins/CustomVariables/Archiver.php

plugins/DBStats/MySQLMetadataProvider.php

plugins/DevicesDetection/Archiver.php

plugins/Goals/Archiver.php

plugins/Provider/API.php

plugins/Provider/Archiver.php

plugins/Referers/API.php

plugins/Referers/Archiver.php

plugins/UserCountry/API.php

plugins/UserCountry/Archiver.php

plugins/UserSettings/API.php

plugins/UserSettings/Archiver.php

plugins/VisitTime/API.php

plugins/VisitTime/Archiver.php

plugins/VisitorInterest/API.php

plugins/VisitorInterest/Archiver.php

...est_OneVisitorTwoVisits__VisitsSummary.getColumns_day.xml