Implement Set Function

[F4n4t]

I noticed that there is a not yet implemented Set Method in the MediaInfoDLL.

I use MediaInfoLib to parse Bluray Images and since the Language is not available in the .m2ts files, i wanted to set it manually. It would also be useful to set the filename for files opened with OpenBuffer.

Currently i parse the JSON and include the missing Information there. But it would be neat if one could Set the information directly and retrieve the TEXT/JSON/XML Output with Inform.

[JeromeMartinez]

We have MediaInfo::Option("File_FileName", "xxx") for setting the file name but not yet something generic.