Congestion Heatmap

[nobodyczcz]

There is a heatmap implementation in planvis 1.3.5.

Currently the heatmap replies on external data to color tiles.

But for the competition, it would be useful if the heat map is generated from the execuated paths of agents. So that we can see the congestion on the map, which are the tiles used more frequently.

Additionally, we can use arrows with different transparency to show the directions of most popular flow for each tile.