Expect to add ed25519 digital signature algorithm

[xflcx1991]

Feature Request

Is your feature request related to a problem? Please describe:

在需要高性能高安全的需求时，ed25519算法是一个很好的选择
Describe the feature you'd like:

实现Go 1.13起（https://pkg.go.dev/golang.org/x/crypto/ed25519），标准库自带的ed25519功能， crypto/ed25519模块。
Describe alternatives you've considered:

暂无
Teachability, Documentation, Adoption, Migration Strategy:

[gouguoyin]

Ed25519 signature and verification have been supported since version 0.2.1

[xflcx1991]

0.2.1 有了ed25519
但是readme ed25519示例代码运行不了

1. 没有dongle.Sign.FromString("hello world").Ed25519(privateKey, dongle.Raw) 方法,应该是 ByEd25519
2. dongle.Raw 是啥,哪里定义的？
   @gouguoyin

[xflcx1991]

// 编码模式常量
const (
RAW encodingMode = "raw"
HEX encodingMode = "hex"
BASE64 encodingMode = "base64"
)

原来是dongle.RAW

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---

// encoding mode constant
const (
RAW encodingMode = "raw"
HEX encodingMode = "hex"
BASE64 encodingMode = "base64"
)
It turned out to be a dongle.RAW

[gouguoyin]

Thanks, the next version will be fixed.

[gouguoyin]

Fixed in v0.2.2

https://github.com/golang-module/dongle/releases/tag/v0.2.2