Fix completion tabbing.

I accidentally broke this in fb3682f5fa9ff702488277521e60c5425cafc64d because
the variable gets reset before the slot is executed now.

See #189.
Use a QObject for quickmarks and add a changed signal.

See #189.
Don't clear page in WebView:shutdown. Fixes #99.

It seems Qt still wants to access the page (for the mousePressEvent) and
segfaults when we clear the page before that's finished.

We now try it inside __del__ like done in the link mentioned in the comment.
Use last focused window for download errors and other stuff.

When the event happens, it's possible we don't have any window focused yet, so
we display it in the window which was last focused.

Fixes #191.
Make srcmodel public in CompletionFilterModel.
importer: Add vim modeline
importer: Use with-block to open file.
pylint_checkers: Fix getting encoding argument.
Show error messages in downloads.
Fix redrawing of downloadview if there are downloads added.
Shut down TabbedBrowser in MainWindow closeEvent.

Hopefully fixes #197.
Set title directly instead of using signals.

See #198, but this didn't fix it.
Draw hints correctly when page is zoomed.

Fixes #199.
hints: fix replacing of {hint-url}.

Fixes #200.
Paste primary selection on Shift+Insert
Merge remote-tracking branch 'florian/master' into quickmark-completion
updating code

according to https://github.com/The-Compiler/qutebrowser/pull/189#issuecomment-59220531