Improve variable cleanup at uninstall

Fix #247578: Print URLs by content type
Fix #298063: Most printed, emailed and PDFd blocks

Fix #336065: change nodeapi content weight to make sure that the content area link is rendered first

Fix #315204: Add options to show only the current page in book links
Fix #314521: Use file:// access when accessing images if private file system is enabled

Fix #318939: Add title tag to icons

Fix bug with visibility where the link was shown when no page was specified but the 'show only in listed pages' was selected

Fix #239896: Make sure drupal_get_title() returns the original page's title

Greybox module
Some misc warnings removed
Added translations

Ability to configure use of text, icon or both in the PF links

Rename the print_fill_attributes function back to the previous name

Fix the 'printable' engine to display the page title.