#145 gluLookAt() Description Inaccurate

[Andy Hammerlindl]

On the page:

http://pyopengl.sourceforge.net/documentation/manual/gluLookAt.3G.html

The equation

s = f x UP

is inaccurate. s should be a unit vector, but it won't
be if f and UP are not perpendicular. It should
probably read

s = f x UP / ||f x UP||

The actual GLU functions in C and in Python appears to
have the proper behaviour.