rework of loader and protocols

• closes #3 (closed)
• Redefining Sample and Delayed sample object's (simpler version)
• Defining an abstract class Loader where is defined the all preprocessing pipeline where parameters are defined in the dictionary of the protocols
• Redefined the Loader for each dataset
• Rework of the train, predict and analyze engine to adapt to new sample object and loader class
• Rework train, predict, analyze and experiment scripts
• add grid-search in train script and remove train-gs script
• rework of the protocols (add dictionary to defined preprocessing protocol)
• rework of the tests