Adding "I-maze" map/environment about lab

[tkoeppe]

@charlesbeattie: could you perhaps have a look?

[dnzrgn]

Hello again,

I have now got it to work. Previously, I just attempted to replicate the "nav_maze_random_goal_01" script (https://github.com/deepmind/lab/blob/master/game_scripts/levels/nav_maze_random_goal_01.lua) by copying it and only changing the entity layer definition.
After following the "Building a Minimal Level" guide (https://github.com/deepmind/lab/blob/master/docs/developers/minimal_level_tutorial.md), I can now create levels with my own entity layer.

[tkoeppe]

Ah, great! Can we close this issue then?

[dnzrgn]

From my side, yes, I don't have anything to add, thanks!

[tkoeppe]

Thanks!