GL_ARB_map_buffer_range
http://www.opengl.org/registry/specs/gl/ARB/map_buffer_range.txt
GL_ARB_map_buffer_range
	GL_MAP_READ_BIT 0x0001
	GL_MAP_WRITE_BIT 0x0002
	GL_MAP_INVALIDATE_RANGE_BIT 0x0004
	GL_MAP_INVALIDATE_BUFFER_BIT 0x0008
	GL_MAP_FLUSH_EXPLICIT_BIT 0x0010
	GL_MAP_UNSYNCHRONIZED_BIT 0x0020
	void glFlushMappedBufferRange (GLenum target, GLintptr offset, GLsizeiptr length)
	GLvoid * glMapBufferRange (GLenum target, GLintptr offset, GLsizeiptr length, GLbitfield access)