[Feature request] Add an option to automatically close the tabs

[hyx0329]

It would be convenient if the tab opened will be closed automatically when:

• the link is handled by external program(custom URL schema)
  • magnet://
  • dict://
• the link is a download link for a file

One approach is utilizing the object returned by browser.tabs.create, setting a timeout action calling browser.tabs.remove(tab_id).

[fnxweb]

OK, that sounds fairly do-able, I'll try to squeeze it in (may not be soon, unfortunately).