Alright...

* Felt like I should commit, after 2 days.
* Server RUNS!!! (after violent refactoring)
  => however not yet tested with client (see below)
* Removed 'Client' on server side, all moved into a 'Session' that holds
  information (= pointers) to 'Character' and 'User'.
  => simplifies client/user/character handling
* Added character representation on client side (in fact, it's used by
  both sides, therefore moved to 'generic').
* Added concept of an 'Area' (world is built up by such 'Areas'
  (squares)).
  => thinking about limited collision handling (maximum number of
     characters per square?)
* But anyway:

CLIENT SIDE IS A HUGE MESS THAT DOESN'T EVEN COMPILE.
It'll get fixed after today's exam.