TestCharTable( tbl )
tbl.centralizers, tbl.classes, tbl.orders and the entries
 of tbl.powermap have same length,tbl.centralizers[i] with tbl.classes[i] is
 equal to tbl.order,tbl.orders[i] divides tbl.centralizers[i],tbl.classnames and the corresponding record fields
 are consistent,tbl.irreducibles is
 satisfied,tbl.irreducibles and
If no inconsistency occurs, true is returned, otherwise each error is
signalled, and false is returned at the end.
    gap> t:= CharTable("A5");; TestCharTable(t);
    true
    gap> t.irreducibles[2]:= t.irreducibles[3] - t.irreducibles[1];;
    gap> TestCharTable(t);
    #E TestCharTable(A5): Scpr( ., X[2], X[1] ) = -1
    #E TestCharTable(A5): Scpr( ., X[2], X[2] ) = 2
    #E TestCharTable(A5): Scpr( ., X[3], X[2] ) = 1
    #E TestCharTable(A5): centralizer orders inconsistent with irreducibles
    false
GAP 3.4.4