Session.php: If QFQ called by api, there is no T3 environment. Therefore there is no logged in FE User. We should keep the found SIP cache and take them (no flush, due to unknown logged in user).

Report.php, Store.php, QuickFormQuery.php: configuration option 'SESSION_NAME' removed and hard coded to 'qfq'.
Session.php, Sip.php: function checkFeUserUid() moved from Sip to Session. Will be called by using 'Session'. SIP's now stored one level deeper in $_SESSION['qfq'][...]. This makes it easier to destroy the SIP cachae in case of login/logout. Destroying the whole $_SESSION var is not a good idea.