Allow network creation

[ibachman]

The code must allow to create networks and interdependent networks as physical-logical interdependent networks that allow for the measurement of the G_L index.

Tasks:

• Create classes for networks and interdependent networks
• Implement network representation for the previous classes
• Add methods to generate networks (Ex. from existing data)
• Add features to simulate network degradation (this may need to be expanded as an issue)