SessionSet
This program sets a session variable. The variable will exist
as long as the PHP session is alive.
The framework tracks only 2 session variables. These are UID, which
is user_id, and PWD, which is user password. An application must be
careful not to overwrite those values, as the framework will make no
provision to prevent such an accident.
string $key - key to set
mixed $value - value to set to $key
function SessionSet($key,$value,$sfx='app') {
$xkey=$GLOBALS["AG"]["application"]."_".$sfx."_".$key;
$_SESSION[$xkey] = $value;
}