Number Checker

Given a number, return a small report describing what kind of number it is. Use simple boolean helper functions, then combine their results in `describeNumber`.

1. `isPositive(number)` should return `true` when the number is greater than `0`.
2. `isNegative(number)` should return `true` when the number is less than `0`.
3. `isZero(number)` should return `true` when the number is exactly `0`.
4. `isEven(number)` should return `true` when the number is even.
5. `describeNumber(number)` should return an object with `positive`, `negative`, `zero`, `even`, and `odd` properties.