Textured Creeper head with colored face

This is a minor modification to the head of the Textured Minecraft Creeper with Moveable Head by Walpeup.

A gap has been added behind the face in Head.stl that accommodates the 1x20x20 Face.stl.

The process is as follows:
1) Print Face.stl in the color of your choice.
2) Slice Head.stl and determine the layer where it would close the gap in the head.
3) Add a pause in your gcode before it starts that layer.
4) Print the Head.stl
5) When it pauses, insert the "face" into the gap and let the print complete.

I printed this on an Original Prusa MK3 sliced with Slic3rPE for a 0.1mm layer height. I found the "before layer start" for ";21.8" and added the following lines:

```
G0 X10.000 Y200.00 E0 ; Home and push the plate forward
M1 ; Pause for user (press the encoder to continue)
G28 Y ; Rehome the Y axis
M105 ; Continue printing
```