Initialize the world

[seletz]

Problem

The world initializaton code is not yet finished.

Tasks

• [ ] Finish the code in the init_welt() function. Use 1 for fish and 2 for sharks
• [ ] Refactor the parts which create fish and sharks to their own functions
• [ ] Now change the fish and shark creation functions to use an array instead of a simple number:
  • sharks: [2, <<alter>>, <<hunger>>]
  • fish: [1, <<alter>>]
• [ ] Change the display function such that it works again