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.
The context related parts of _GLFWwndconfig have been moved to
_GLFWctxconfig and given better names. Window hint and attribute
members have been renamed to match.
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.
The default behavior of WGL, EGL and GLX is to choose a config that has
/at least/ the specified number of bits, whereas the GLFW 2 behavior was
to choose the closest match with very few hard constraints. Moving the
responsibility of finding the supported minimum values to the client was
problematic, as there's no way to enumerate supported configurations,
forcing the client to perform multiple (and slow) window/context
creation attempts. Not even the currently set defaults (24-bit color
and depth, 8-bit stencil) is universally supported, as bug reports show.
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.
