Adds tiles which provide power to whatever's sitting on top of them. Also adds a power tap to feed these tiles

• Powered Floor Tile: Powers objects on top and neighboring tiles

• Powered Floor Circuit Tile: Also transmits red & green circuit signals to neighboring tiles.
  (Does not feed these to objects on top.)

• Powered Floor Tap: A stubby electric pole that transmits power to the tiles, and circuit signals to/from the circuit tiles.

Changes

Version 0.3.8 Factorio 0.18 support. Fix graphics issue with blocks of circuit tiles

Version 0.3.7 Factorio 0.17 support

Version 0.2.6 Fix crash (Thanks, SereneRebel!)

Version 0.2.5 Hide the wires (Thanks, OwnlyMe!)

Version 0.1.4 Removed errant debug message

Version 0.1.3 fixes bug introduced wiht Factorio 0.16.17

Version 0.1.2 now supports Factorio 0.16