Totals at top of page, various bug fixes & Dutch translation

* Enhancement: Added totals per transient type at the top of the page
* Bug fix: duplicate nonce
* Bug fix: show some useful information about invalid transients
* Fixes for a number of HTML validation errors.
	* missing `<tr>` in `<thead>`
	* missing `</span>` in $action_links
* Also made it so css will auto-zebra-stripe the table without the need for a class name in each row
* Regenerated .pot file
* Added Dutch translation