Only generate Doxyfile if generating docs.

Fixes #307.
Formatting.
Fixed modifier key events being lost.
Clarified dependency list.
Removed tautological test.
Consume WM_ERASEBKGND.
Added GLFW_AUTO_ICONIFY.

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.
Added GLFW_DONT_CARE.

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.
Added GLFW_DOUBLEBUFFER.
Added GLFW_FLOATING.

Fixes #23.
Added position testing to windows test.
Made windows test show all windows at once.
Updated glad.
Fixed plural forms on key/button arrays.
Fixed cursor outside new full screen windows.

The cursor was not positioned over newly created full screen windows,
leading to confusing behavior like invisible cursor or window
iconification.

This fix is a stop-gap until the direct cursor position work is merged.

Fixes #111.
Setting CSS for missed elements.
Doxygen CSS cleanup.
Introducing extra.less and using Less CSS for higher flexibility.

This will reduce the amount of copy paste involved when performing
slight changes to the default color sets.

These Ruby gems are required for generating extra.css from extra.less:
gem install less therubyracer

Please run this command to regenerate extra.css:
lessc --compress extra.less > extra.css
Formatting.
Fixed use of previous member name.