Draw the map in the dijkstra tests

Try to draw the map in the differents tests and draw the pawns moving on it.

Tests2.html pathfinding got broken.

On first page load, the map doesn't draw because the tileset loading is async and we ask the map to draw itself without waiting for the tileset to finish loading. 
Just refresh after first load, this way the tileset is already in the browser cache and chances are higher it will have loaded when we first ask map to draw itself. (Use Promises ?)
Also i removed the creation of <canvas> elements on each Graph.drawDebug because it felt weird and useless... but if it's the right way, no problem