add new port: games/tome4-beta

This adds a beta of 1.6 patch for games/tome4

It's a major update. Read more in announcements:
https://te4.org/blogs/darkgod/2019/04/news/whats-next-tales-majeyal-lot-and-then-some
https://te4.org/blogs/darkgod/2019/09/news/tales-majeyal-16-beta1-upon-you