Let R have class d, and L a partition of [1..d].
FusionScheme(R, L) returns the fusion of R by L.
For example, use it like as FusionScheme(R, [[1],[2,3],[4,5,6]]).
0 is always fixed.
Note that this function does not check whether the result is a scheme.
To do it, use the function IsAssociationScheme.
