Improved cookies filtering for domain mismatch and for tracking cookies,
it is now fully (i hope) working and ready to use in everyday browsing.
Please test it by yourself and report any issues.
Also fixed crash when closing cookies manager window with "Close" in
title bar or with Alt+F4
When going to fullscreen, add tab button will no longer stay on screen,
and also when going back to normal screen, list tabs button will no
longer be hidden.
Using now qobject_cast everywhere possible instead of c++ type cast
Middle mouse click in bookmarks manager (library + sidebar + toolbar)
and history manager (library + sidebar) now opens a new tab