Display only player's vision - Zappy GUI

[Thomaltarix]

Is your feature request related to a problem? Please describe.
If we want to play the game like the AI can do, we need to have the vision of the players.

Describe the solution you'd like
I'll add a condition when displaying tiles, players, tiles content, etc...
If the position of the object is not in the range of the player's vision (based on his level), then don't display it.