Use strings builder

[ninedraft]

Hello! I'm suggesting to use the strings.Builder instead of bytes.Buffer. It's a more efficient alternative with very low cast costs.

[huandu]

strings.Builder is available since go1.10. It can be a break change for packages or projects importing this package.

Please consider to implement a helper builder which calls strings.Builder if it's available and uses bytes.Buffer as a fallback.

[ninedraft]

strings.Builder is available since go1.10. It can be a break change for packages or projects importing this package.

Please consider to implement a helper builder which calls strings.Builder if it's available and uses bytes.Buffer as a fallback.

done ✅

[huandu]

Very cool! Thank you.

I have several comments on filenames of the newly added files.

• According to Go best practice, when we need to build code for specific Go version, we should add version as suffix in a name like buffer_go110.go. Therefore, buffer.go and buffer_old.go should be renamed as buffer_go110.go and buffer.go respectively.
• Filename should be consistence with type name. The buffer is not a right name as the type defined in this file is bufferString. BTW, I think it would be better to name the type as stringBuilder and the file as stringbuilder.go.

[ninedraft]

Very cool! Thank you.

I have several comments on filenames of the newly added files.

* According to Go best practice, when we need to build code for specific Go version, we should add version as suffix in a name like `buffer_go110.go`. Therefore, `buffer.go` and `buffer_old.go` should be renamed as `buffer_go110.go` and `buffer.go` respectively.

* Filename should be consistence with type name. The `buffer` is not a right name as the type defined in this file is `bufferString`. BTW, I think it would be better to name the type as `stringBuilder` and the file as `stringbuilder.go`.

done ✅