Integrating atoum's tests framework
Creating and adding some basical tests to TreeBuilder
Use of exceptions instead of ugly exit()
Adding tests TreeBuilder::addNode() method
Adding all missing test's methods and two new assertions
to avoid void methods
Adding two methods to checks if a node belongs to the builder
Adding Node's changes and corresponding tests
Improve Node::setPArentNode() tests
Adding ability to get the graph's order
+ split export's method to compute's method and export's method
+ changes on many tests
Changes filename of the example file ("test" to "example")
+ adding required TreeBuilder::compute() call
Merge branch 'feature-adding-unit-tests' into develop