[plt-scheme] rotate90 is clockwise on einstein; CCW on zorro

[Jens Axel Soegaard]

I have found and fixed the bug(s). The new version is now available
at PLaneT as version 2.1.

A very small test suite is included. Please write if, you find more
errors.

#lang scheme
(require (planet "test.ss" ("soegaard" "sicp.plt" 2 1)))

-- 
Jens Axel Søgaard