Section 2

-Provisionally introduced subsection titles for easier navigation;
- started to rewrite the main results without using involution;
- inserted Lemma 2.21 showing that invariant subspaces are
 complemented if an integral exists
- inserted corollary 2.23 showing that X is isomorphic to (S^2 otimes
 id)(X)  without using involutions
- rewrote Schur orthogonality without involutions