Feature/hooks

[andria-dev]

Migrated code to hooks.

Changes

• useReducer to handle complicated state without cluttering component
  • logic like incrementing/decrementing enemies is in reducer
  • so is checking the answer and creating a new problem
• Moved logic (reducer) to separate file AppReducer.js
• Placed handlers (i.e. handleModePicker) in useCallback calls to avoid re-rendering when not necessary
• Created operatorsByMode, an object that matches a mode to an operator, to replace the lengthy switch statement to find out which mode belongs to which operator.
• Replaced lengthy switch statement that checks if the entered answer matches the expected answer. The new solution uses eval to evaluate the problem with the dynamic variable operator
• Made the random number generator allow a minimum as well, numbers are now inclusive -> randomNumberGenerator(1, 9) returns 1 <= x <= 9

Notes

Changing to hooks makes React DevTools not able to see non-primitive values of hooks, to remedy this you should use an experimental version of React DevTools (it looks better too lol)

I also added a prettier.config.js file to make it so that when a contributor saves it doesn't reformat the entire file to their editor's style, but instead keeps it in the same style you've been writing code in (no semicolons, single quotes, tab width of 2).