glPrioritizeTextures - set texture residence priority

	  void glPrioritizeTextures( GLsizei n,
				     const GLuint *textures,
				     const GLclampf *priorities	)

	  n	      Specifies	the number of textures to be

	  textures    Specifies	an array containing the	names of the
		      textures to be prioritized.

	  priorities  Specifies	an array containing the	texture
		      priorities.  A priority given in an element of
		      priorities applies to the	texture	named by the
		      corresponding element of textures.

	  glPrioritizeTextures assigns the n texture priorities	given
	  in priorities	to the n textures named	in textures.

	  The GL establishes a ``working set'' of textures that	are
	  resident in texture memory.  These textures may be bound to
	  a texture target much	more efficiently than textures that
	  are not resident.  By	specifying a priority for each
	  texture, glPrioritizeTextures	allows applications to guide
	  the GL implementation	in determining which textures should
	  be resident.

	  The priorities given in priorities are clamped to the	range
	  [0,1]	before they are	assigned.  0 indicates the lowest
	  priority; textures with priority 0 are least likely to be
	  resident.  1 indicates the highest priority; textures	with
	  priority 1 are most likely to	be resident.  However,
	  textures are not guaranteed to be resident until they	are

	  glPrioritizeTextures silently	ignores	attempts to prioritize
	  texture 0, or	any texture name that does not correspond to
	  an existing texture.

	  glPrioritizeTextures does not	require	that any of the
	  textures named by textures be	bound to a texture target.
	  glTexParameter may also be used to set a texture's priority,
	  but only if the texture is currently bound.  This is the
	  only way to set the priority of a default texture.

	  glPrioritizeTextures is available only if the	GL version is
	  1.1 or greater.

	  GL_INVALID_VALUE is generated	if n is	negative.

	  GL_INVALID_OPERATION is generated if glPrioritizeTextures is
	  executed between the execution of glBegin and	the
	  corresponding	execution of glEnd.

	  glGetTexParameter with parameter name	GL_TEXTURE_PRIORITY
	  retrieves the	priority of a currently	bound texture.

	  glAreTexturesResident, glBindTexture,	glCopyTexImage1D,
	  glCopyTexImage2D, glTexImage1D, glTexImage2D,	glTexParameter