Remove empty chests from the map

[netzakh]

(I originally wanted to suggest using a different picture, but what about text mode etc.)

[Omega Blue]

I was thinking about that as well

[Infinitum]

In the same vein, maybe show locked chest locations through the fog of war? I usually make sure to autoexplore the entire map before opening any, and finding them manually can be a pain (esp. on labyrinth 1).