Bug[ring]: NTTLazy returns values outside of the range [0, 2q-1]

[Pro7ech]

To be clear, this is not a correctness issue and it can also be treated as a documentation issue and cleared by updating the documentation to the range [0, 4q-2]. However the convention for the suffix lazy in Lattigo usually means the output values are expected to be in the range [0, 2q-1]. Predictable range is especially important when doing lazy additions, to know how many additions can be done without modular reduction before values wrap around u64.

package main

import(
	"fmt"
	"github.com/tuneinsight/lattigo/v6/ring"
)

func main(){
	n := 16
	r, err := ring.NewRing(n, []uint64{65537})

	if err != nil{
		panic(err)
	}

	p := r.NewPoly()

	for i := range n{
		p.Coeffs[0][i] = uint64(i)
	}

	r.NTTLazy(p, p)

	fmt.Println(p)
}