Hunger change

Changes the hunger system in various ways:
* New hunger hud icons. 
* Food w/o sugar can be loaded into the Chef's compartment of snack vending machines by anyone and bought like regular snacks.
* Rearranging datum/reagents and splitting the huge Chemistry-Reagents.dm into smaller files, all "good" medical reagents are under datum/reagent/medicine/ and all food&drink reagents are under datum/reagent/consumable. Removed some unnecessary code in Chemistry-Reagents.dm .
* Adding a pizza crate to cargo orders and creating children to /obj/item/pizzabox to contain each type of pizza. (taken from baystation12)
* Adding two new var for mobs "satiety" and "metabolism_efficiency".
* Adding one new reagent "vitamin". It boosts satiety. It has the same probability as nutriment to heal brute damage but also burn damage. It doesn't affect nutrition.
* Changing the "sugar" reagent. Its nutrition boost depends on how fed you are. If well fed, you get no boost. The more hungry you are, the bigger the boost. Sugar intake lowers your satiety. 
* Growns and cooked food are given vitamins while junk food are all given sugar. 
* Slightly lowering snack food amounts in snack vending machines.
* Slightly lowering nutriment amount in junk food (compensated by adding sugar to them)
* Adding another nutrition level between the current 'full' and 'fat' level (max nutrition before going into fat territory is now 550 instead of 450).

* metabolism_efficiency affects the metabolization speed of healing and damaging reagents (like toxins), the radiation effect from reagents that deals radiation and the efficiency of bodytemp stabilization via calory use. Higher metabolism_efficiency means medicine reagents stay longer in your body and the opposite for damaging reagents, less radiation from radium or uranium, faster stabilization of bodytemperature. metabolism_effiency gets higher when fed and positively satiated and lower when starving or fat. The metabolism_efficiency can have three values currently: 0.8 , 1 (default) and 1.25 .

* satiety handles hunger rate, if negative your nutrition is drained five times faster than default (does not affect nutrition changes due to movements). A high positive satiety plus being fed boosts the metabolism efficiency. Vitamin intake raises satiety, sugar intake lowers eat. satiety naturally changes toward 0 over time. When satiety is greatly negative you cannot eat more sugary food (unless you are starving) and must wait for satiety to go up again. A positive satiety lowers your chance to spread viruses. satiety is bound between -200 and 600. If you binge eat sugar and get -200 satiety, you will lose 100 nutrition points over the next 6min30 (instead of 20pts).

* If you eat/drink too much sugary food (junk food from snack vending machine mostly), you won't be able to eat/drink more sugary food and will have to wait a bit unless you're starving. Example: you reach this point after eating one and a half 4noraisin. The waiting time cannot be higher than 2mins.

* Adding vitamin reagents to most grown and cooked food. Vitamin intake raises satiety. If you manage to get max satiety and stop eating vitamin, you will keep all satiety related bonuses for up to 16mins.
* Adding or boosting sugar amounts in junk food.

What this means:
* The different foods are now balanced, the more easily acquired the food, the more drawbacks it has:
- easily acquired junk food gives a fast and significant nutrition boost but its sugar means getting hungry again sooner and prevents easily reaching the top nutrition and satiety levels.
- donkpocket are junk food unless it is microwaved then you won't be hungry again fast but no satiety boost. 
- chef recipes boost satiety and nutrition quickly and the more complex the recipe the bigger the boost.
- Most botanist's growns boost satiety and nutrition but less thand chef food unless high potency. 
-  easily acquired drinks generally give a decent but slow nutrition boost , no satiety change. (exception for hot coco that's closer to junk food) 
- dry ramen is similar to drinks, but hot ramen (dry ramen water) gives a higher nutrition boost 
- You can order a costly pizza crate for a big nutrition and satiety boost.
* You won't starve even if there's no chef or botanist.
* Players are incentivized to get better food
* Poisoning the chef's food undetected is easier by placing it in snack machines and people will eat those more often than junk food.