Visualizer upgrade

[wschella]

The visualization page could use some upgrades.

• Stylize buttons/page
• Implement Fog-of-War
• Implement reset button (see Resetknop in visualizer #109)

[iasoon]

Fog of war is already implemented in the arbitrator. You can simply feed the data stream it sends to a player into the visualiser.

It might be good to avoid doubly implementing game logic - it may change in the future.

[iasoon]

Loading long logs is slow as well.
This could be solved by incrementally parsing the log file, but that would prevent us from showing the battle length.
Perhaps we need a new log format?