BPT_SessionManager: Manage user access sessions

*** Use case ***

Using this class is very simple, after you have included it, you have to call only

$smngr = SessionManager::get_instance();

to obtain a SessionManager instance and automatically start a new session. If you want to verify if session starts correctly you can use this method

$smngr->is_started();

You can manipulate registered variables using this method

$smngr->var_is_registered("foo");
$smngr->register_var("foo","foo");
$smngr->get_var("foo");
$smngr->unregister_var("foo");

to clear all variables, just call

$smngr->clear();

*** Protection Mode ***

Protection mode is an easy way to ensure that some code run only after a condition is verified, for example a page that require a valid login. In this case, if user has submitted a valid login information you can use

$smngr->start_protection()

Now, in all pages that require a valid login, call

$smngr->is_protected()

to verify the condition. you can pass a url (e.g. "http://www.google.it") as parameter to is_protected() function if you want to force url redirection in case of test fail.