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...
Minor update to reuse the RNG type declaration
Make Agent::getType virtual for greater flexibility
Get rid of some compilation warnings
Merge pull request #103 from gfrances/warnings

Get rid of some compilation warnings
Merge pull request #101 from montanier/master

check version of scons before using InstallVersionLib
minor modification ot the gitignore
merge modifications from upstream