Make EncoderJNI and EncoderJNI.Wrapper public

[deshanxiao]

Motivation:

This PR is aimed to mark EncoderJNI and EncoderJNI.Wrapper as public class since DecoderJNI and DecoderJNI.Wrapper are already public class. Meanwhile it also mark methods from EncoderJNI.Wrapper as public.

Modification:

Add public modifier in EncoderJNI and EncoderJNI.Wrapper. Add public modifier in methods of EncoderJNI.Wrapper.

Result:

Fixes #123

[deshanxiao]

cc @hyperxpro

[hyperxpro]

You might wanna make methods public too.

[deshanxiao]

@hyperxpro Thanks, updated the PR and description.

[hyperxpro]

Thanks!