FACE customization (eyes / nose / mouth) for a custom race/model.

Folder is the RACE id; the file names are prefixed with the CUSTOM MODEL name (same rule as
the body skins one folder up). They live under DragonMineZ's own namespace:
  assets/dragonminez/textures/entity/races/<race>/faces/<model>_<part>_<index>...png

1. This example ships as race "example_race" using model "example_model" (see the sibling
   example_model_*_layer1.png body skins). Copy the example_race/ folder, rename it to YOUR
   race id, and rename the files' prefix to YOUR Custom Model name.
2. File names, exactly:
     <model>_eye_<index>_<layer>.png   layer is 0,1,2,3 (all four make up one eye option)
     <model>_nose_<index>.png
     <model>_mouth_<index>.png
   <index> starts at 0 and counts up (0,1,2,...) for each extra option.
3. In /sdu race -> Body tab, the Eyes/Nose/Mouth pickers list the <index> values you added.

The shipped placeholders (example_model_nose_0.png, _mouth_0.png, _eye_0_0..3.png) are fully
TRANSPARENT - that's why the example face is blank. Paint them to give it a face.
(A race with NO Custom Model uses the race id itself as the prefix instead.)
