Fixed setCurrentUri() in buildSideMenu()

With this fix, the active side menu item is shown correctly even if

* the script name is in the URI (e.g., app_dev.php),
* the script directory is below the web root (e.g., /backend/) and
* the URI contains parameters (e.g., ?param1=value&param2=value).
Merge pull request #1131 from to0om/sidemenu_bugfix

Fixed setCurrentUri() in buildSideMenu()