Revisiting network functions

[vmgaribay]

This is low priority, but some items caught my attention as room for improvement in clarity/flexibility of the following:

random_edge_noise.py
Action Plan:

1. find a graceful way to differentiate between ratio calculation options for random edge noise (e.g., ratio*current links, ratio * possible links, ratio * nodes, etc.)

link_deletion.py
Action Plan:

1. understand potential purpose of weighted and multinomial methods

2. write clearer description of weighted and multinomial methods

3. test weighted and multinomial methods

4. fix not implemented error if weight and multinomial are functioning correctly

5. see if there is a smart way to make balance part of the link deletion function instead of performing threshold calculations within the step (would require initial_edges parameter