include all low-level bindings

include all low-level bindings

* figl/parse.scm (parse-prototypes, skip?): Remove the skip? function,
  include all low-level bindings.  In many cases automatic skip is not
  possible, such as glMaterial that requires both packed and unpacked
  variants depending on the parameter.  Some variants are encouraged
  to be optimized (such as glColor3b).  Any low-level consumer can
  decide whether to use packed/unpacked, and what format to store data
  in.  Let the foot shooting commence.

* figl/gl/types.scm: Include more possible type combinations, whether
  used directly by gl or not.

* figl/gl/low-level.scm: Update.

* doc/: Not updated due to problems with line wrapping in texi output.