Variables created within a DLL with __declspec(thread) may not get a TLS
slot on Windows XP, leading to segfaults on use. Moving to TlsAlloc
works around this.
The public, platform, native, event and utility functions are already
documented in-source. Having duplicate documentation inevitably means
having them contradict one another. Furthermore, most of the function
descriptions simply repeated the name of the function.
Renamed _glfwLibrary to _glfw and made all substructs lower-case, making
global variable names easier to read and type. Partially inspired by the
internal naming conventions of glwt.
