ENH: Module 'connection_m' was cleaned up, so the dummy Neuron class was moved to the separate module 'neuron_dummy_m'.

ENH: Added Makefiles and Connection module separated into two file - one with module itself and the other one for testing purposes.

ENH + FIX: Added comment to multiple methods + fixed constructor implementation for the class IntervalConnection.

    contains:
        - module Connection_mod with classes Connection and
          IntervalConnection

    TODO:
        - delete dummy Neuron class after its implementation
        - fully comment the code