Support added for different unit of measures

The following unit of measures are now supported as amount types in recipes:

• Liter
  • dl
  • msk
  • tsk
  • krm
• Gram
  • kg

Example: Both of these are valid and correspond to the same amount:

"Water": {"amount": 8, "amount_type": "dl"}
"Water": {"amount": 0.8, "amount_type": "liter"}