[Sessions] - Sessions are now stored locally cache/sessions in WDDX. Btw, there is a security need to put cache outside the web directory in prod environment. - Cleaning sessions on perso change

[Login]

• Last username and OpenID stored in a cookie, to have a login form autofill

[Story]

• Stories are located in XML document, by global locations and are like gamebooks/livre dont vous êtes le héro. TODO: l10n
• This document xml matches 3 PHP classes: Story, StorySection StoryChoice, located in includes/story
• First test (incomplete) story: Zeta, Kaos