moved dimensions into a subdirectory

core/Columns/Updater.php

core/Db/Schema/Mysql.php

core/Plugin/Dimension/ActionDimension.php

core/Plugin/Dimension/ConversionDimension.php

core/Plugin/Dimension/VisitDimension.php

core/Plugin/Manager.php

core/Plugin/Report.php

core/Tracker/Action.php

core/Tracker/GoalManager.php

core/Tracker/Visit.php

core/Tracker/Visitor.php

core/Updates/2.5.0-b1.php

plugins/API/API.php

plugins/Actions/Columns/ClickedUrl.php

plugins/Actions/Columns/DestinationPage.php

plugins/Actions/Columns/DownloadUrl.php

plugins/Actions/Columns/EntryPageTitle.php

plugins/Actions/Columns/EntryPageUrl.php

plugins/Actions/Columns/ExitPageTitle.php

plugins/Actions/Columns/ExitPageUrl.php