(Modded) Empire Section floor tiles

Thanks to theavatar111 for the design!

These are however slightly modified:

- Rivets around the 'plates' are organized so they make a 2mm offset to each other when multiple plates are put next to each other.

- "... tiles_var_2" has hight adjusted and flattened to work with the other tiles as one print.

- "... tiles_var_2 and 3" has a mirror image with rivets aligned as the other tiles.

- "... tiles_var_3 and 4" are extras to achieve a better transition and to make holes in the flooring.

Enjoy!