Fix build on Mac OS X 10.7 Lion.

`CVDisplayLinkRef` needs an extra header file, and `NSAppKitVersionNumber10_7`
wasn't added until 10.8so use `> NSAppKitVersionNumber10_6` instead.
Merge pull request #159 from metajack/fix-10-7-build

Fixed build on OS X 10.7.
More words on window closing.
Updated extension headers.
Documentation updates.
Moved GLFW compilation guide to docs.
Cleaned up Win32 timer.
Added Lion full scren menu item.
Added credit.
Clarified WGL re-creation comment.
Added NULL test for glGetStringi.
Placed glfwinfo version test after getopt.
Added flag descriptions to glfwinfo -h.
Fixed hidden window positioning on Metacity.
Removed fixed @bug.
Added Compiz to bug fix entry.
Added reporting of extension string retrieval failure.
Fixed crash retrieving the name of some displays.
Added workaround for 10.9 SDK type definitions.
Moved to Cocoa for transformation and activation.