Renamed "phpBb" Plugin

* it is now simply named "phpbb" instead of "data-import-phpbb"
Better "User must be authenticated" policy implementation

* The "'auth.middleware.is-authenticated' middleware now stores the attempted Request path in Session, and redirects to the "sign in" form instead of throwing an Exception
Bugfixes for the previously renamed "phpBb" Plugin
Added some performances probes, renamed "PluginData" class to "Plugin"

* we now report some performances informations in "$app['perfs.*']" keys
* we display them in our main layout when $app['debug'] === true
* added a simplistic app data cache control through the app "main.ini.php" bootstrap config file
* added "enabledOnlyForUrl" & "enabledOnlyForItsActionsUrlsPrefix" properties to Plugins config files schema
* "/phpinfo" Action moved to "utils" Plugin
* the flag used to conditionally enable a Action is renamed from "debugOnly" to "onlyForDebug"
* added a "perfs" Service to "utils" Plugin
* usual CS fixes