Revert "Correct the rotation matrix and use sinpi/cospi."

This reverts commit 96adbcd4c61427958e43b83201d9147c027f865c.
Revert "Forio REPL is no more. Use JuliaBox."

This reverts commit 17ca45b5d14bc4acc2fdaa8f60434b6f069560d7.
Revert "New landing page. Fixes #69 and #94"

This reverts commit 38652f71ae27f1102df13801e57ce26a1662ad57.