Refactored badly designed agent iteration register
Adjusted Marc's code to new iteration interface

Also converted tab indentation to 4 spaces and fixed a bunch of PEP8 lint warnings
Refactored Scenario/World object relations

* Scenario now creates the world and can easily modify the size of the
world etc.
* Scenarios are now loaded dynamically from the scenarios catalog
* Split up existing scenarios into individual files for easier code
management
* Cleaned up some more PEP8 lint warnings (tab indentations etc.)
Removed annoying debug output from A* lib