MixerWagon Fix

Adds functionality to the mixerwagon.

Functions:
- Mixing time: The ingredients for mixed rations now actually need to be mixed for a set amount of time (see below) before they become mixed rations.
- Decay: Leaving mixed rations in a mixerwagon for too long (see below), will result in it clumping up and unbinding, requiring more mixing. Nothing will be lost, it just requires mixing again.

Times:
- Mixing time: Easy: 15s, Normal: 30s, Hard: 60s.
- Decay
- Starts after: Easy: 6h, Normal: 4h, Hard: 2h.
- Fully decayed after: Easy: 36h, Normal: 24h, Hard: 12h.

Notes:
- Should automatically work on all mixerwagons that have the 'mixerWagon' specialization.
- Mixing status can be seen in the F1 help menu box.