Release date for Arrow 5.0 and LZ4_RAW option

[Yuan, Hangjian]

Hi Apache Arrow community,

Thank you for the effort of making such a great open-source framework. :)

I found Parquet C++ lib in Apache Arrow 5.0 will provide LZ4_RAW option for 
compressing parquet files, which should be compatible with Hadoop. Can I get a 
rough release date for version 5 or LZ4_RAW option?

Thanks,
Hangjian