Add pathfinding informations & improve debug tool look

[Mardelor]

Improve OUTech debug tool & simulation view - closes #68 :

• Add css & layout to the debug tool
• Add graph informations to the simulation's view. It can be filtered for performance purpose. To be printable, entry json file should have an event with following syntax :

  {
  "time": 1.23,
  "key": "graph",
  "value": {
      "nodes": [
          {
              "id": 0,
              "position": {
                  "x": 100,
                  "y": 200
              },
              "neighbours": [ 1, 2 ]
          },
          {
              "id": 1,
              "position": {
                  "x": 100,
                  "y": 300
              },
              "neighbours": [ 0, 2 ]
          },
          {
              "id": 2,
              "position": {
                  "x": 200,
                  "y": 250
              },
              "neighbours": [ 0, 1 ]
          }
      ]
  }
  }