This changes the behavior of framebuffer hints set to zero. Before,
zero meant that any value was acceptable. This changes zero to be an
explicit preference and adds GLFW_DONT_CARE to mean that any value is
equally acceptable.
Fixes#70.
By default, full screen windows that lose focus will be iconified and
the video mode will be restored. This makes it impossible to create
applications spanning multiple monitors. The GLFW_AUTO_ICONIFY window
hint will allow users to disable this behavior.
Fixes#143.
Parameters are something specified at creation time and are often
immutable, while many of the values returned by glfwGetWindowParam
reflected current state not controlled by any parameter or hint.
