Add support for obtaining window size options.

[gdamore]

This builds upon PR #45, but it could also be rebased ahead if desired. This adds a nice way for us to get the Window size, which is very useful for applications like tcell.

There is some gofmt noise, as my editor automatically runs go fmt to clean things up. If that is bothersome, let me know and I'll strip that out.

[tj]

👍 would be great to have a consolidated package for the lower level functionality, seems that most people inline this stuff in larger projects but with all the compatibility issues that's a huge pain

[gdamore]

It is indeed a huge pain. It looks like the maintainer of this package is not interested in PRs submitted from other folks -- which is his right certainly. If anyone else is watching this space and thinking of contributing here, it is probably something to be aware of.

[giulianopz]

It is indeed a huge pain. It looks like the maintainer of this package is not interested in PRs submitted from other folks -- which is his right certainly. If anyone else is watching this space and thinking of contributing here, it is probably something to be aware of.

This repo should be archived since now Go has official support to interact with terminals: https://github.com/golang/term.