S, an instance of the type LieSubSpace, an instance of type LieSubSpace, a Lie subspace of the source of $f$
Outputs:
I, an instance of the type LieSubSpace, an instance of LieSubSpace, the image $f(S)$, a Lie subspace of the target of $f$
Description
If $S$ is of type FGLieSubAlgebra, then image(f,S) is of type FGLieSubAlgebra. If $S$ is an instance of LieSubAlgebra, but not of FGLieSubAlgebra, then image(f,S) is of type LieSubAlgebra. Otherwise, image(f,S) is of type LieSubSpace.