refs #5820 added documentation and improved code

core/Cache/CacheDecorator.php

core/Cache/CacheInterface.php

core/Cache/LanguageAwareStaticCache.php

core/Cache/PersistentCache.php

core/Cache/PluginAwareStaticCache.php

core/Cache/StaticCache.php

core/Columns/Dimension.php

core/Plugin/Dimension/ActionDimension.php

core/Plugin/Dimension/ConversionDimension.php

core/Plugin/Dimension/VisitDimension.php

core/Plugin/Report.php

core/Plugin/Segment.php

core/Plugin/ViewDataTable.php

plugins/Actions/Columns/ServerTime.php

plugins/Actions/Columns/TimeSpentRefAction.php

plugins/Actions/Columns/VisitTotalActions.php

plugins/Actions/Columns/VisitTotalSearches.php

plugins/CoreHome/Columns/IdSite.php

plugins/CoreHome/Columns/VisitFirstActionTime.php

plugins/CoreHome/Columns/VisitGoalBuyer.php