update v17.3

"Discord Suggestions" is a short serie that will feature random prompts from
the #suggestions channel on our Discord Server.

The aim of this serie is to chop down the long suggestion list, without
having to wait a specific theme.

Each batch will last 5-10 updates and is planned on a bi-monthly basis (~)

-

- Added a small Power House
- Added an Electric Box (2 sizes)
- Updated the themes and single files with the new stuff

See you and happy game-making! :)