[0.18.26] chemical-plant.oog - Popping sound on loop

[seal]

Whenever an entity uses the chemical-plant.oog file as a looped sound at the end of every loop there is a loud pop sound that happens.

I fixed the issue on my side by adding a 0.0005 sec fade in and out at the beginning and end of the file.

[posila]

Fixed for 0.18.37