automatic glut initialization

automatic glut initialization

* figl/glut/runtime.scm (resolve): Run a hook before resolving glut
  symbols.  Remove the plural define-glut-procedures.

* figl/glut.scm: Rename glut-init to initialize-glut, and add keyword
  arguments for initial window size, position, and display mode.
  Default to (program-arguments) for args.  Make the glut-init? marker
  global, not thread-local.  Add resolve hook to initialize-glut as
  needed.

* examples/glut/demo.scm: Update.