Added comparison operators for numbers and funjects

Funjects have the following comparison operators:

- a.is b: `true` if and only if a is the same funject as b
- a.isnt b: the opposite of `.is`
- a == b: `true` if a and b are equal
- a != b: the opposite of `==`

Numbers have the following additional comparison operators:

- a < b
- a <= b
- a > b
- a >= b