Split topics updates fix#1871

@emanuele45 this is to fix http://www.elkarte.net/community/index.php?topic=2154.0

There were a few things in play with that controller, and it still needs to be improved in 1.1 I think.  As it was it had this dependency to  get form values, validate them, save them in context place them in the next form step, get them, re validate them, save them again for the next form step, etc.  In doing this the post names changed and other stuff which got a bit confused, well at least I did :angel: 

This moves most of that initial form processing to a single step and saves the values in session which is easier to deal with when you have several steps of forms.  I also made a couple of tweaks of the subs which were also checking $_Post values so I pulled some of that logic back to the controller.

Anyway, this needs some testing !