Add 'lights on' mode

[strakam]

Original implementation of generals.io and this simulator is such that all games are partially observable (there is a fog-of-war).

It would be cool if there was a 'lights on' mode, where all the information is available to all agents (no fog-of-war).
This would bring nice things:

• New game mode, where agents can use tree search algorithms like minimax or dijkstra
• Make easier version of the game, where it should be easier to debug stuff.

Note: the 'lights on' mode is just one mode of many possible. Other modes like "see only owned squares and nothing else" would be a straightforward addition.