move islot_comestible::nutr to islot_comestible::kcal

[KorGgenT]

Summary

SUMMARY: Infrastructure "internally store kcal instead of nutr values"

Purpose of change

Since the move to Calories being the energy type derived from food, nutrition is slowly losings its meaning. i am replacing nutr with kcal as the actual value that the game uses. This is mainly because kcal is a larger number, and with it will reduce rounding errors with the various calculations that food does. The obvious change that players will see is that foods will increase in displayed calories anywhere from 0-8 kcal per food item. As of right now this does not affect hunger, but in future PRs it will.

Describe the solution

Find instances where nutr is called and substitute for kcal. some areas where nutr is used stay the same, and a new get_nutrition() function is made in itype for quick and easy translation

Additional Context

because of the change, it was necessary to make some more edits to recipes in order to pass the unit tests.

[KorGgenT]

so i sorta want #28519 to go through before i start fixing up the travis test fails, but i suppose it's not strictly required