GLFW thread safe

Hello, for go.wde (github.com/skelterjohn/go.wde), which defenetly works with goroutines and is thereby multithreading, I added a glfw3 backend. glfw3 itself has very good documentation about what needs to run in the main thread and what not. To make it work with go.wde I applied the functionality which is described in https://code.google.com/p/go-wiki/wiki/LockOSThread.

The question now is whether or not we should implement this functionality in the main repository or to just leave it forked?