1. Refactor import_class into an util module.
1. Change name of Dataset.deploy() to Dataset.load() to avoid confusion with node deployment.
2. Correction of some bugs in dataset module.
3. Refactorization of xp into xp and xp_wrapper. The first method performs the experiment, the wrapper does macro replacement and manages repetitions.
4. Pre_load function is moved to util and can be defined as a parameter to StaticDataset class.