Small refactoring of the way agents are print to ostreams, so that it allows for easier overloading.
Refactored the config parsing methods to reuse code.
Added a method for parsing unsigned integers.
Updated gitignore file
bugfix
Made some World methods virtual to allow subclasses to overload them
Made the config parsing methods more flexible.

This allows for more complex use cases such as iterating over several children nodes with the same name.
A small modification to get rid of unused variable warnings.
Merge pull request #100 from gfrances/master

Small refactoring of the way agents are print to ostreams, so that it al...