Migrate glfw3 back to the core

[tomyun]

Seems glfw3 was moved out to homebrew/versions since it failed to support Snow Leopard (#20626). As far as I understand correctly, the official support is currently down to Mountain Lion and it'll be also moved up to Mavericks when El Capitan comes out. Then I think it'd be fine to move glfw3 back to the core as glfw. There are some new softwares that could be potentially benefitted by having it.

[MikeMcQuaid]

👍 from me. Feel free to open a PR.

[DomT4]

My only concern is that we handle reverse migration pretty terribly. Anything which points to homebrew/versions/glfw3 in any core tap as a dependency would need fixing.

[LinusU]

I would love seeing this as well, hopefully I can take a stab at it and submit a pull request.

[DomT4]

Feel free. I'm 👎 on the rename though as that'll break existing installations. You'd also need to check each Homebrew tap for glfw3 deps and stop them pointing at the Versions tap.