Vent block

[Trent VanSlyke]

Allows gas to pass through, but not mobs. Should be full-block sized. Should be able to base it off gas pipe easily.

[Erlend Åmdal]

This is more like a Gases Framework thing. Not exactly easy to integrate with current gas physics.

[Trent VanSlyke]

Aye, accidentally put it in the wrong repo.