Poseidon Sponge Hash with different frame sizes (#52)

* Poseidon Sponge Hash with different frame sizes
* Update deps. Bump go version
* Update & fix linter.
* Refactor a bit.
* Reduce gc pressure

constants/constants.go

@@ -1,31 +1,19 @@
 package constants
 
 import (
-	"fmt"
 	"math/big"
 )
 
+const qString = "21888242871839275222246405745257275088548364400416034343698204186575808495617"
+
 // Q is the order of the integer field (Zq) that fits inside the SNARK.
-var Q *big.Int
+var Q, _ = new(big.Int).SetString(qString, 10)
 
 // Zero is 0.
-var Zero *big.Int
+var Zero = big.NewInt(0)
 
 // One is 1.
-var One *big.Int
+var One = big.NewInt(1)
 
 // MinusOne is -1.
-var MinusOne *big.Int
-
-func init() {
-	Zero = big.NewInt(0)
-	One = big.NewInt(1)
-	MinusOne = big.NewInt(-1)
-
-	qString := "21888242871839275222246405745257275088548364400416034343698204186575808495617"
-	var ok bool
-	Q, ok = new(big.Int).SetString(qString, 10) //nolint:gomnd
-	if !ok {
-		panic(fmt.Sprintf("Bad base 10 string %s", qString))
-	}
-}
+var MinusOne = big.NewInt(-1)