[typo] cache mechanism in production mode

[Alex Deva]

I'm not very sure how the caching works with Typo, but it certainly  
doesn't work the same if in production or development mode.

In development, everything works as expected; however, in production  
mode, pages in cache don't expire when they should. I changed the  
default template to show login/logout links, and the name of  
whoever's logged in at the moment, and unless I clear the cache  
manually, it shows the user as logged in even after he logs out, and  
viceversa. Again, this only happens in production mode. If I disable  
caching, things work fine.

Any insights?