Revert "Use scrollRequested signal instead of paintEvent."

It seems on some pages like Twitter or blog.fdik.org, the
QWebPage::scrollRequested signal never gets emitted, so we use this for now.

Fixes #400.
See https://bugreports.qt-project.org/browse/QTBUG-43521.

This reverts commit 03fb21c476b5487eed5ad2957f6c4b62d9ed5221.

Conflicts:
	qutebrowser/browser/webview.py
Force-include pygments in freeze.py.

Fixes #398.
Handle category being None in Qt message handler.

Fixes #397.
Ignore clicks on failed downloads.

Fixes #396.
Actually connect QWebView.on_config_changed slot.
Adjust page zoom if default zoom changed.

Fixes #393.
Set zoom to default instead of 100% with :zoom/=.
Don't treat things like "31c3" as IP address.

Fixes #388.