JavaScript privacy options in preferences

Solving #682.

Things to note:

1. user(s) can manually open/close windows, disregarding chosen options (but if opening/closing of the pages is disabled pages wont be able to open/close windows automatically, or at least I think so)
2. I don't know whether or not ``javascript copying to clipboard`` works or not, I did not tested it.
3. still I would like to find a way to block javascripts trying to acces right-click event