Sponet

Added features:
- enforcing no isolates in the Erdos Renyi generator for faster generation

Changes:
- file reorganization (**may break imports**)
- stochastic approximation of opinion shares

Changes:
- fixed bug with sample_many_runs that used the same rng for each subprocess

Changes:
- fixed rng parameter of sample_many_runs
- improved performance of Bianconi-Barabasi generator

Changes:
- added Generator for Bianconi-Barabasi random networks

Changes:
- Replaced log complexity sampling with O(1) sampling via Alias method. This makes the previous version of the const complexity simulation obsolete.