Unit test dev_trade branch

[Negnamazi]

Two main developments have implemented in this branch:

1. Adding the possibility to determine which pair of regions are going to be connected to each other and which energy carriers would be traded among them

2. Adding the coordination to the nodes

These developments are manually tested with both built in examples and some other external case studies but the main unit test must be written by @mohammadamint before merging to the main branch