* Removed references to `set_state`
* Split some functionality from `agents` into separate files (`fsm` and
`network_agents`)
* Rename `neighboring_agents` to `neighbors`
* Delete some spurious functions
* Graphs are not saved by default (not backwards compatible)
* Modified newsspread examples
* More granular options to save results (exporting to CSV and GEXF are now
optional)
* Updated tutorial to include exporting options
* Removed references from environment to simulation
* Added parallelism to simulations (can be turned off with a flag or argument).