Convert floating point and integer numbers into bytes and put them into an array
let a: &[u8] = &fi2b![1, 2, 1.0, -1.0]; assert_eq!( a, [1u8, 0u8, 0u8, 0u8, 2u8, 0u8, 0u8, 0u8, 0u8, 0u8, 128u8, 63u8, 0u8, 0u8, 128u8, 191u8] )