Creation of ButtonsLearning

- created the class ButtonsLearning which hold the buttons associated
with learning in a GraphicNN
- added getter for QTimr in GraphicNN to modifiy its properties with the
buttons of the ButtonsLearning
- added forward declaration in the GraphicNeuron class
- created in a function the LearningSample file to transform a
QList<QList<double>*>* into a QList<LearningSample>*
Comments

- Commented some files
- Grouped all buttons on ButtonsLearning