Fast Implementation of Base58 encoding

Fast implementation of base58 encoding in Go.

Base algorithm is adapted from https://github.com/trezor/trezor-crypto/blob/master/base58.c

Benchmark

• Trivial - encoding based on big.Int (most libraries use such an implementation)
• Fast - optimized algorithm provided by this module

BenchmarkTrivialBase58Encoding-4          123063              9568 ns/op
BenchmarkFastBase58Encoding-4             690040              1598 ns/op

BenchmarkTrivialBase58Decoding-4          275216              4301 ns/op
BenchmarkFastBase58Decoding-4            1812105               658 ns/op

Encoding - faster by 6 times

Decoding - faster by 6 times

Usage example

package main

import (
	"fmt"
	"github.com/mr-tron/base58"
)

func main() {

	encoded := "1QCaxc8hutpdZ62iKZsn1TCG3nh7uPZojq"
	num, err := base58.Decode(encoded)
	if err != nil {
		fmt.Printf("Demo %v, got error %s\n", encoded, err)	
	}
	chk := base58.Encode(num)
	if encoded == string(chk) {
		fmt.Printf ( "Successfully decoded then re-encoded %s\n", encoded )
	} 
}