CLI commands for graphs modules

[gitond]

at least the following commands need to be included

• [x] command for creating new vertex
• [x] datastructures in state machine to make storing graph data possible. See #21
• [x] command for creating new graph
• [x] command to use graph.price()
• [x] command to use graph.maxPrice()
• [x] command to use graph.length()
• [x] command to use graph.neighbor() --- Up to this point after solving issue #14 ---
• [x] visualisation command
• [x] IF DEEMED POSSIBLE / NECESSARY also add command to save visualisation to image file --- Up to this point after solving issue #15 ---
• [ ] random adjacency matrix command
• [ ] random graph generator command --- Up to this point after solving issue #16 ---
• [ ] save graph to file command
• [x] load graph from file command --- Up to this point after solving issue #18 ---