refs #2714, refs #3073

 * flat settings are passed to graph views and exports
 * csv renderer does not do flattening anymore. the new api parameters can be used instead - js and tests updated accordingly
 * aggregate rows are italic (imo, the plus logo would be misleading because it would suggest clickability)
 * disable row evolution on flat tables for performance reasons
 * minor language adjustments

git-svn-id: http://dev.piwik.org/svn/trunk@6181 59fd770c-687e-43c8-a1e3-f5a4ff64c105