Fixes #3004, redesigned DBStats plugin, added several new reports including...

Fixes #3004, redesigned DBStats plugin, added several new reports including database space taken up by tracker tables, database space taken up by archive blob tables, database space taken up by archive metric tables, database space taken up by individual reports & database space taken up by individual metrics.

Notes:

  * Added ability to highlight the summary row in ViewDataTable and the ability to always show the summary row regardless of what report page is currently being shown.
  * Fixed small issue w/ ViewDataTable::hasReportBeenPurged: default values should be specified in calls to getRequestVar.
  * Added Piwik_FetchAssoc function to PluginsFunctions/Sql.php
  * Augmented ColumnCallbackAddColumnQuotient filter so the divisor can be obtained from the summary row.
  * Modified AddSummaryRow filter so it wouldn't delete rows if desired.
  * Added ColumnCallbackAddColumn filer that adds a new column to each row based on the result of a callback.
  * Modified ColumnCallbackReplace filter so callback can operate on more than one column value if desired.
  * Modified Limit filter so, if desired, the summary row can be exempted from deletion.
  * Added GroupBy filter that groups/sums rows by the result of a callback function.
  * Fixed GenerateGraphData.php bug where priority filters were not called on view data table.
  * Added getPrettyNumber utility function.



git-svn-id: http://dev.piwik.org/svn/trunk@6324 59fd770c-687e-43c8-a1e3-f5a4ff64c105