r4092 new API for dispaying messages (showError, showWarning, showSuccess)

r4092 new API for dispaying messages (showError, showWarning, showSuccess)

index.php:
 merged together all HTML layout
 added output buffering to collect all the messages before the HTML layout rendering

process.php:
 used new functions instead of oneLiner.
 added logic to redirect to the submit form page when ophandler returns NULL

render_image.php:
 changed old showError calls to the calls of new one

inc/interface.php:
 showTabs: removed surrounding <td>'s from the output
 renderObject8021QSync: changed old showError calls to the calls of new one
 renderDiscoveredNeighbors: idem

inc/auth.php:
 authenticated_via_ldap: changed old showError calls to the calls of new one

inc/init.php:
 -showError: the old version of the func removed, the new one is implemented in functions.php
 -showWarning: idem

inc/functions.php:
 getCellFilter: changed old showWarning calls to the calls of new one
 buildLVSConfig: idem
 eval_expression: idem
+setMessage: function for rendering or queueing all kinds of messages
+showError, showWarning, showSuccess, showNotice: wrappers around setMessage

upgrade.php:
-showFailure
 changed calls to showFailure to calls to showError
 added dependency on functions.php

inc/ophandlers.php:
 buildWideRedirectURL: now $_SESSION['log'] is merged with $log, not substituted