Function: algdecomposition
Section: algebras
C-Name: alg_decomposition
Prototype: G
Help: algdecomposition(al): semisimple decomposition of the algebra al.
Doc: \var{al} being a table algebra output by \tet{algtableinit}, returns
 $[J,[al_1,\dots,al_n]]$ where $J$ is a basis of the Jacobson radical of
 \var{al} and $al_1,\dots,al_n$ are the simple factors of the semisimple
 algebra $al/J$.
