There was an existing recipe for crafting an mp3 player, but
surprisingly none for a much simpler device, the vibrator.
This recipe uses similar ingredients to the existing deconstruction
recipe (with the addition of a tiny electric motor), and is auto-learned
at fabrication level 2.

Makes the recipe a bit more realistic, and balanced with existing
recipes, based on pull request comments from other players and
further inspection of existing recipes. Changes include:

- Require a plastic mold (must-have for a smoothly contoured shape)
  and additional plastic scraps to account for mold overrun
- Require electronics skill 1, but use fab 2 to construct
- Increase difficulty to 3 and crafting time to 20 minutes
- Need wire, solder, and soldering iron
- Use "motor_micro" (0.28 lbs) instead of "motor_tiny" (1.38 lbs),
  since vibrator itself only weighs 1.0 lbs