Make Piwik_Tracker_Visit::handleKnownVisit hookable #1440

As mentioned in #1436, it would be nice if the update function (Piwik_Tracker_Visit::handleKnownVisit) would be hookable. Here is a patch to do so.

Attachment: patch for /core/Tracker/Visit.php
Visit.php.patch

(In [2391]) Fixes #1440 Adding hook to update the visitor row in Tracker

Thanks for the patch - I had to make 2 changes to the patch as it was throwing php NOTICE ($sqlQuery was not defined, and $sqlActionUpdate was not defined)