[lib] Use macro instead of float for constants to allow compile time evaluation.

[forFudan]

Define constants.

Use alias for compile time evaluation of indefinite precision.

import numojo as nm
fn main():
    var pi: Float64 = nm.pi
    print("Float64:", pi*pi*pi*pi*pi*pi)
    print("Literal:", nm.pi*nm.pi*nm.pi*nm.pi*nm.pi*nm.pi)

Float64: 961.38919357530415
Literal: 961.38919357530449